ref-manual: add references to variables only documented in the BitBake manual

This makes the Yocto Project manual variable list and index more useful,
not missing any potentially useful variable.

The price to pay is that a reference to such variables now has to go through
the intermediate reference in the Yocto Project variable list, instead
of going straight to the Bitbake manual.

(From yocto-docs rev: 3d308812cd9aa906890a0f8562fc28c1cd8aaab6)

Signed-off-by: Michael Opdenacker <michael.opdenacker@bootlin.com>
Reviewed-by: Quentin Schulz <foss+yocto@0leil.net>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

documentation/ref-manual/variables.rst

@@ -353,6 +353,18 @@ system and gives an overview of their function and contents.
       host listed in :term:`SRC_URI` after a successful fetch from the
       :term:`PREMIRRORS` occurs.
 
+   :term:`BB_BASEHASH_IGNORE_VARS`
+      See :term:`bitbake:BB_BASEHASH_IGNORE_VARS` in the BitBake manual.
+
+   :term:`BB_CHECK_SSL_CERTS`
+      See :term:`bitbake:BB_CHECK_SSL_CERTS` in the BitBake manual.
+
+   :term:`BB_CONSOLELOG`
+      See :term:`bitbake:BB_CONSOLELOG` in the BitBake manual.
+
+   :term:`BB_CURRENTTASK`
+      See :term:`bitbake:BB_CURRENTTASK` in the BitBake manual.
+
    :term:`BB_DANGLINGAPPENDS_WARNONLY`
       Defines how BitBake handles situations where an append file
       (``.bbappend``) has no corresponding recipe file (``.bb``). This
@@ -371,6 +383,12 @@ system and gives an overview of their function and contents.
 
          BB_DANGLINGAPPENDS_WARNONLY = "1"
 
+   :term:`BB_DEFAULT_TASK`
+      See :term:`bitbake:BB_DEFAULT_TASK` in the BitBake manual.
+
+   :term:`BB_DEFAULT_UMASK`
+      See :term:`bitbake:BB_DEFAULT_UMASK` in the BitBake manual.
+
    :term:`BB_DISKMON_DIRS`
       Monitors disk space and available inodes during the build and allows
       you to control the build based on these parameters.
@@ -492,6 +510,18 @@ system and gives an overview of their function and contents.
       a respective interval is reached beyond the initial warning (i.e. 1
       Gbytes and 100 Kbytes).
 
+   :term:`BB_ENV_PASSTHROUGH`
+      See :term:`bitbake:BB_ENV_PASSTHROUGH` in the BitBake manual.
+
+   :term:`BB_ENV_PASSTHROUGH_ADDITIONS`
+      See :term:`bitbake:BB_ENV_PASSTHROUGH_ADDITIONS` in the BitBake manual.
+
+   :term:`BB_FETCH_PREMIRRORONLY`
+      See :term:`bitbake:BB_FETCH_PREMIRRORONLY` in the BitBake manual.
+
+   :term:`BB_FILENAME`
+      See :term:`bitbake:BB_FILENAME` in the BitBake manual.
+
    :term:`BB_GENERATE_MIRROR_TARBALLS`
       Causes tarballs of the source control repositories (e.g. Git
       repositories), including metadata, to be placed in the
@@ -511,6 +541,48 @@ system and gives an overview of their function and contents.
       clean up your :term:`DL_DIR` directory by deleting any Git or other
       source control work directories.
 
+   :term:`BB_GENERATE_SHALLOW_TARBALLS`
+      See :term:`bitbake:BB_GENERATE_SHALLOW_TARBALLS` in the BitBake manual.
+
+   :term:`BB_GIT_SHALLOW`
+      See :term:`bitbake:BB_GIT_SHALLOW` in the BitBake manual.
+
+   :term:`BB_GIT_SHALLOW_DEPTH`
+      See :term:`bitbake:BB_GIT_SHALLOW_DEPTH` in the BitBake manual.
+
+   :term:`BB_HASHCHECK_FUNCTION`
+      See :term:`bitbake:BB_HASHCHECK_FUNCTION` in the BitBake manual.
+
+   :term:`BB_HASHCONFIG_IGNORE_VARS`
+      See :term:`bitbake:BB_HASHCONFIG_IGNORE_VARS` in the BitBake manual.
+
+   :term:`BB_HASHSERVE`
+      See :term:`bitbake:BB_HASHSERVE` in the BitBake manual.
+
+   :term:`BB_HASHSERVE_UPSTREAM`
+      See :term:`bitbake:BB_HASHSERVE_UPSTREAM` in the BitBake manual.
+
+   :term:`BB_INVALIDCONF`
+      See :term:`bitbake:BB_INVALIDCONF` in the BitBake manual.
+
+   :term:`BB_LOGCONFIG`
+      See :term:`bitbake:BB_LOGCONFIG` in the BitBake manual.
+
+   :term:`BB_LOGFMT`
+      See :term:`bitbake:BB_LOGFMT` in the BitBake manual.
+
+   :term:`BB_MULTI_PROVIDER_ALLOWED`
+      See :term:`bitbake:BB_MULTI_PROVIDER_ALLOWED` in the BitBake manual.
+
+   :term:`BB_NICE_LEVEL`
+      See :term:`bitbake:BB_NICE_LEVEL` in the BitBake manual.
+
+   :term:`BB_NO_NETWORK`
+      See :term:`bitbake:BB_NO_NETWORK` in the BitBake manual.
+
+   :term:`BB_NUMBER_PARSE_THREADS`
+      See :term:`bitbake:BB_NUMBER_PARSE_THREADS` in the BitBake manual.
+
    :term:`BB_NUMBER_THREADS`
       The maximum number of tasks BitBake should run in parallel at any one
       time. The OpenEmbedded build system automatically configures this
@@ -556,6 +628,33 @@ system and gives an overview of their function and contents.
       tasks already being run from using all CPU threads on the system
       if :term:`PARALLEL_MAKE` is not set to a low value.
 
+   :term:`BB_ORIGENV`
+      See :term:`bitbake:BB_ORIGENV` in the BitBake manual.
+
+   :term:`BB_PRESERVE_ENV`
+      See :term:`bitbake:BB_PRESERVE_ENV` in the BitBake manual.
+
+   :term:`BB_PRESSURE_MAX_CPU`
+      See :term:`bitbake:BB_PRESSURE_MAX_CPU` in the BitBake manual.
+
+   :term:`BB_PRESSURE_MAX_IO`
+      See :term:`bitbake:BB_PRESSURE_MAX_IO` in the BitBake manual.
+
+   :term:`BB_PRESSURE_MAX_MEMORY`
+      See :term:`bitbake:BB_PRESSURE_MAX_MEMORY` in the BitBake manual.
+
+   :term:`BB_RUNFMT`
+      See :term:`bitbake:BB_RUNFMT` in the BitBake manual.
+
+   :term:`BB_RUNTASK`
+      See :term:`bitbake:BB_RUNTASK` in the BitBake manual.
+
+   :term:`BB_SCHEDULER`
+      See :term:`bitbake:BB_SCHEDULER` in the BitBake manual.
+
+   :term:`BB_SCHEDULERS`
+      See :term:`bitbake:BB_SCHEDULERS` in the BitBake manual.
+
    :term:`BB_SERVER_TIMEOUT`
       Specifies the time (in seconds) after which to unload the BitBake
       server due to inactivity. Set :term:`BB_SERVER_TIMEOUT` to determine how
@@ -569,6 +668,36 @@ system and gives an overview of their function and contents.
       If you want the server to never be unloaded,
       set :term:`BB_SERVER_TIMEOUT` to "-1".
 
+   :term:`BB_SETSCENE_DEPVALID`
+      See :term:`bitbake:BB_SETSCENE_DEPVALID` in the BitBake manual.
+
+   :term:`BB_SIGNATURE_EXCLUDE_FLAGS`
+      See :term:`bitbake:BB_SIGNATURE_EXCLUDE_FLAGS` in the BitBake manual.
+
+   :term:`BB_SIGNATURE_HANDLER`
+      See :term:`bitbake:BB_SIGNATURE_HANDLER` in the BitBake manual.
+
+   :term:`BB_SRCREV_POLICY`
+      See :term:`bitbake:BB_SRCREV_POLICY` in the BitBake manual.
+
+   :term:`BB_STRICT_CHECKSUM`
+      See :term:`bitbake:BB_STRICT_CHECKSUM` in the BitBake manual.
+
+   :term:`BB_TASK_IONICE_LEVEL`
+      See :term:`bitbake:BB_TASK_IONICE_LEVEL` in the BitBake manual.
+
+   :term:`BB_TASK_NICE_LEVEL`
+      See :term:`bitbake:BB_TASK_NICE_LEVEL` in the BitBake manual.
+
+   :term:`BB_TASKHASH`
+      See :term:`bitbake:BB_TASKHASH` in the BitBake manual.
+
+   :term:`BB_VERBOSE_LOGS`
+      See :term:`bitbake:BB_VERBOSE_LOGS` in the BitBake manual.
+
+   :term:`BB_WORKERCONTEXT`
+      See :term:`bitbake:BB_WORKERCONTEXT` in the BitBake manual.
+
    :term:`BBCLASSEXTEND`
       Allows you to extend a recipe so that it builds variants of the
       software. There are common variants for recipes as "natives" like
@@ -599,6 +728,9 @@ system and gives an overview of their function and contents.
          since ``include`` statements are processed when the recipe is
          parsed.
 
+   :term:`BBDEBUG`
+      See :term:`bitbake:BBDEBUG` in the BitBake manual.
+
    :term:`BBFILE_COLLECTIONS`
       Lists the names of configured layers. These names are used to find
       the other ``BBFILE_*`` variables. Typically, each layer will append
@@ -674,6 +806,9 @@ system and gives an overview of their function and contents.
              /work/my-layer/bbappends/meta-security-isafw/*/*/*.bbappend
              /work/my-layer/bbappends/openembedded-core/meta/*/*/*.bbappend
 
+   :term:`BBINCLUDED`
+      See :term:`bitbake:BBINCLUDED` in the BitBake manual.
+
    :term:`BBINCLUDELOGS`
       Variable that controls how BitBake displays logs on build failure.
 
@@ -698,6 +833,9 @@ system and gives an overview of their function and contents.
       This example enables four layers, one of which is a custom,
       user-defined layer named ``meta-mykernel``.
 
+   :term:`BBLAYERS_FETCH_DIR`
+      See :term:`bitbake:BBLAYERS_FETCH_DIR` in the BitBake manual.
+
    :term:`BBMASK`
       Prevents BitBake from processing recipes and recipe append files.
 
@@ -754,6 +892,9 @@ system and gives an overview of their function and contents.
       ":ref:`dev-manual/building:building images for multiple targets using multiple configurations`"
       section in the Yocto Project Development Tasks Manual.
 
+   :term:`BBPATH`
+      See :term:`bitbake:BBPATH` in the BitBake manual.
+
    :term:`BBSERVER`
       If defined in the BitBake environment, :term:`BBSERVER` points to the
       BitBake remote server.
@@ -767,6 +908,9 @@ system and gives an overview of their function and contents.
       Consequently, :term:`BBSERVER` is excluded from checksum and dependency
       data.
 
+   :term:`BBTARGETS`
+      See :term:`bitbake:BBTARGETS` in the BitBake manual.
+
    :term:`BINCONFIG`
       When inheriting the
       :ref:`binconfig-disabled <ref-classes-binconfig-disabled>` class,
@@ -804,6 +948,9 @@ system and gives an overview of their function and contents.
       information on the class in the
       ":ref:`ref-classes-binconfig`" section.
 
+   :term:`BITBAKE_UI`
+      See :term:`bitbake:BITBAKE_UI` in the BitBake manual.
+
    :term:`BP`
       The base recipe name and version but without any special recipe name
       suffix (i.e. ``-native``, ``lib64-``, and so forth). :term:`BP` is
@@ -1051,6 +1198,9 @@ system and gives an overview of their function and contents.
 
          BUILDHISTORY_PUSH_REPO ?= ""
 
+   :term:`BUILDNAME`
+      See :term:`bitbake:BUILDNAME` in the BitBake manual.
+
    :term:`BUILDSDK_CFLAGS`
       Specifies the flags to pass to the C compiler when building for the
       SDK. When building in the ``nativesdk-`` context,
@@ -1092,6 +1242,9 @@ system and gives an overview of their function and contents.
       splitting the output executable file. Set the variable to "0" to get
       a single output executable file.
 
+   :term:`BZRDIR`
+      See :term:`bitbake:BZRDIR` in the BitBake manual.
+
    :term:`CACHE`
       Specifies the directory BitBake uses to store a cache of the
       :term:`Metadata` so it does not need to be parsed every time
@@ -2461,6 +2614,24 @@ system and gives an overview of their function and contents.
 
          EXTRANATIVEPATH = "foo bar"
 
+   :term:`FAKEROOT`
+      See :term:`bitbake:FAKEROOT` in the BitBake manual.
+
+   :term:`FAKEROOTBASEENV`
+      See :term:`bitbake:FAKEROOTBASEENV` in the BitBake manual.
+
+   :term:`FAKEROOTCMD`
+      See :term:`bitbake:FAKEROOTCMD` in the BitBake manual.
+
+   :term:`FAKEROOTDIRS`
+      See :term:`bitbake:FAKEROOTDIRS` in the BitBake manual.
+
+   :term:`FAKEROOTENV`
+      See :term:`bitbake:FAKEROOTENV` in the BitBake manual.
+
+   :term:`FAKEROOTNOENV`
+      See :term:`bitbake:FAKEROOTNOENV` in the BitBake manual.
+
    :term:`FEATURE_PACKAGES`
       Defines one or more packages to include in an image when a specific
       item is included in :term:`IMAGE_FEATURES`.
@@ -2496,6 +2667,12 @@ system and gives an overview of their function and contents.
       a set of configuration files for you in your target that work with
       the feed.
 
+   :term:`FETCHCMD`
+      See :term:`bitbake:FETCHCMD` in the BitBake manual.
+
+   :term:`FILE`
+      See :term:`bitbake:FILE` in the BitBake manual.
+
    :term:`FILES`
       The list of files and directories that are placed in a package. The
       :term:`PACKAGES` variable lists the packages
@@ -2903,6 +3080,9 @@ system and gives an overview of their function and contents.
       method modules being installed when the modules are in packages other
       than the main package.
 
+   :term:`HGDIR`
+      See :term:`bitbake:HGDIR` in the BitBake manual.
+
    :term:`HOMEPAGE`
       Website where more information about the software the recipe is
       building can be found.
@@ -4456,6 +4636,9 @@ system and gives an overview of their function and contents.
       available outside of ``layer.conf`` and references are expanded
       immediately when parsing of the file completes.
 
+   :term:`LAYERDIR_RE`
+      See :term:`bitbake:LAYERDIR_RE` in the BitBake manual.
+
    :term:`LAYERRECOMMENDS`
       Lists the layers, separated by spaces, recommended for use with this
       layer.
@@ -5349,6 +5532,9 @@ system and gives an overview of their function and contents.
 
          ${PN}-${PV}
 
+   :term:`P4DIR`
+      See :term:`bitbake:P4DIR` in the BitBake manual.
+
    :term:`PACKAGE_ADD_METADATA`
       This variable defines additional metadata to add to packages.
 
@@ -5915,6 +6101,9 @@ system and gives an overview of their function and contents.
       denotes the path to ``dist/`` (short for distribution) where the
       binary archive ``wheel`` is built.
 
+   :term:`PERSISTENT_DIR`
+      See :term:`bitbake:PERSISTENT_DIR` in the BitBake manual.
+
    :term:`PF`
       Specifies the recipe or package name and includes all version and
       revision numbers (i.e. ``glibc-2.13-r20+svnr15508/`` and
@@ -6118,6 +6307,9 @@ system and gives an overview of their function and contents.
          desirable since this mechanism is designed to select between mutually
          exclusive alternative providers.
 
+   :term:`PREFERRED_PROVIDERS`
+      See :term:`bitbake:PREFERRED_PROVIDERS` in the BitBake manual.
+
    :term:`PREFERRED_VERSION`
       If there are multiple versions of a recipe available, this variable
       determines which version should be given preference. You must always
@@ -6539,6 +6731,9 @@ system and gives an overview of their function and contents.
       in the ":ref:`ref-manual/devtool-reference:checking on the upgrade status of a recipe`"
       section.
 
+   :term:`REPODIR`
+      See :term:`bitbake:REPODIR` in the BitBake manual.
+
    :term:`REQUIRED_DISTRO_FEATURES`
       When inheriting the :ref:`features_check <ref-classes-features_check>`
       class, this variable identifies distribution features that must exist
@@ -7444,6 +7639,9 @@ system and gives an overview of their function and contents.
       section in the Yocto Project Board Support Package Developer's Guide
       for additional information.
 
+   :term:`SRCREV_FORMAT`
+      See :term:`bitbake:SRCREV_FORMAT` in the BitBake manual.
+
    :term:`SRC_URI`
 
       See the BitBake manual for the initial description for this variable:
@@ -7826,6 +8024,9 @@ system and gives an overview of their function and contents.
       :term:`PV`, and :term:`PR` for related variable
       information.
 
+   :term:`STAMPCLEAN`
+      See :term:`bitbake:STAMPCLEAN` in the BitBake manual.
+
    :term:`STAMPS_DIR`
       Specifies the base directory in which the OpenEmbedded build system
       places stamps. The default directory is ``${TMPDIR}/stamps``.
@@ -8601,6 +8802,9 @@ system and gives an overview of their function and contents.
       information on setting up a cross-development environment, see the
       :doc:`/sdk-manual/index` manual.
 
+   :term:`TOPDIR`
+      See :term:`bitbake:TOPDIR` in the BitBake manual.
+
    :term:`TRANSLATED_TARGET_ARCH`
       A sanitized version of :term:`TARGET_ARCH`. This
       variable is used where the architecture is needed in a value where