ccache: move environment variables to the configuration file

Move some environment variables to the configuration file, so there's
less happening in the class.

Max_size was removed so that the per-recipe caches don't grown without
limit. The default cache is 5GB.

(From OE-Core rev: 8c1c38a6b3073d2dd34514f5a90805c12c0f42dd)

Signed-off-by: Ross Burton <ross.burton@arm.com>
Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/ccache.bbclass

@@ -44,16 +44,6 @@ export CCACHE_CONFIGPATH ?= "${COREBASE}/meta/conf/ccache.conf"
 
 export CCACHE_DIR ?= "${CCACHE_TOP_DIR}/${MULTIMACH_TARGET_SYS}/${PN}"
 
-# Fixed errors:
-# ccache: error: Failed to create directory /run/user/0/ccache-tmp: Permission denied
-export CCACHE_TEMPDIR ?= "${CCACHE_DIR}/tmp"
-
-# We need to stop ccache considering the current directory or the
-# debug-prefix-map target directory to be significant when calculating
-# its hash. Without this the cache would be invalidated every time
-# ${PV} or ${PR} change.
-export CCACHE_NOHASHDIR ?= "1"
-
 python() {
     """
     Enable ccache for the recipe

meta/conf/ccache.conf

@@ -1,7 +1,14 @@
-max_size = 0
-
 # Avoid spurious cache misses caused by recipe sysroot creation: Creating a
 # recipe sysroot hardlinks all dependent files into place. Hardlinking updates
 # the file's ctime which in turn interferes with ccache's include_file_ctime
 # check.
 sloppiness = include_file_ctime
+
+# We need to stop ccache considering the current directory or the
+# debug-prefix-map target directory to be significant when calculating
+# its hash. Without this the cache would be invalidated every time
+# ${PV} or ${PR} change.
+hash_dir = false
+
+# If ccache runs under pseudo it will try to create files in /run/user/0/ccache-tmp
+temporary_dir = $CCACHE_DIR/tmp