RDKOSS-578: Include meta-clang needed for secclient-rs

Reason for change:
The clang compiler is required for the secclient-rs module. This commit integrates the meta-clang recipe, which provides compiler version 1.72.0.

Signed-off-by: mselva006c <mani_selvaraj@comcast.com>

Author: mselva006c

conf/template/bblayers.conf.sample

@@ -73,3 +73,4 @@ BBLAYERS =+ " \
     ${@d.getVar('MANIFEST_PATH_REGION_CONFIG') if d.getVar('MANIFEST_PATH_REGION_CONFIG') is not None and os.path.isfile(d.getVar('MANIFEST_PATH_REGION_CONFIG') + '/conf/layer.conf') else ''} \
     "
 BBLAYERS =+ "${@d.getVar('MANIFEST_PATH_META_MIXIN') if d.getVar('MANIFEST_PATH_META_MIXIN') is not None and os.path.isfile(d.getVar('MANIFEST_PATH_META_MIXIN') + '/conf/layer.conf') else ''}"
+BBLAYERS =+ "${@d.getVar('MANIFEST_PATH_META_CLANG') if d.getVar('MANIFEST_PATH_META_CLANG') is not None and os.path.isfile(d.getVar('MANIFEST_PATH_META_CLANG') + '/conf/layer.conf') else ''}"