ref-manual: Added new glossary entries for HOSTTOOLS* variables.

Entry added for HOSTTOOLS and HOSTTOOLS_NONFATAL.

(From yocto-docs rev: c766920a13071c1bb46a195ea07be38962d2e12d)

Signed-off-by: Scott Rifenbark <srifenbark@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

documentation/ref-manual/ref-variables.xml

@@ -5115,6 +5115,53 @@
             </glossdef>
         </glossentry>
 
+        <glossentry id='var-HOSTTOOLS'><glossterm>HOSTTOOLS</glossterm>
+            <info>
+                HOSTTOOLS[doc] = "A space-separated list (filter) of tools on the build host that should be allowed to be called from within build tasks."
+            </info>
+            <glossdef>
+                <para role="glossdeffirst">
+<!--                <para role="glossdeffirst"><imagedata fileref="figures/define-generic.png" /> -->
+                    A space-separated list (filter) of tools on the build host
+                    that should be allowed to be called from within build tasks.
+                    Using this filter helps reduce the possibility of host
+                    contamination.
+                    If a tool specified in the value of
+                    <filename>HOSTTOOLS</filename> is not found on the
+                    build host, the OpenEmbedded build system produces
+                    an error and the build is not started.
+                </para>
+
+                <para>
+                    For additional information, see
+                    <link linkend='var-HOSTTOOLS_NONFATAL'><filename>HOSTTOOLS_NONFATAL</filename></link>.
+                </para>
+            </glossdef>
+        </glossentry>
+
+        <glossentry id='var-HOSTTOOLS_NONFATAL'><glossterm>HOSTTOOLS_NONFATAL</glossterm>
+            <info>
+                HOSTTOOLS_NONFATAL[doc] = "A space-separated list (filter) of tools on the build host that should be allowed to be called from within build tasks."
+            </info>
+            <glossdef>
+                <para role="glossdeffirst">
+<!--                <para role="glossdeffirst"><imagedata fileref="figures/define-generic.png" /> -->
+                    A space-separated list (filter) of tools on the build host
+                    that should be allowed to be called from within build tasks.
+                    Using this filter helps reduce the possibility of host
+                    contamination.
+                    Unlike
+                    <link linkend='var-HOSTTOOLS'><filename>HOSTTOOLS</filename></link>,
+                    the OpenEmbedded build system does not produce and error
+                    if a tool specified in the value of
+                    <filename>HOSTTOOLS_NONFATAL</filename> is not found on the
+                    build host.
+                    Thus, you can use <filename>HOSTTOOLS_NONFATAL</filename>
+                    to filter optional host tools.
+                </para>
+            </glossdef>
+        </glossentry>
+
         <glossentry id='var-HOST_VENDOR'><glossterm>HOST_VENDOR</glossterm>
             <info>
                 HOST_VENDOR[doc] = "The name of the vendor. Normally same as the TARGET_VENDOR."