agl-selinux: pull in meta-clang

agl-selinux: pull in meta-clang

Make pulling in meta-clang for the agl-selinx feature explicit, to
avoid dependency issues from the uutils-coreutils recipe in meta-oe.
This fixes building when configured with just the "agl-ic-container"
feature without "agl-demo".

Bug-AGL: SPEC-5123

Change-Id: Ie775b2e3ceb081448fc8b772f9686ad4dfbb45dc
Signed-off-by: Scott Murray <scott.murray@konsulko.com>
Reviewed-on: https://gerrit.automotivelinux.org/gerrit/c/AGL/meta-agl/+/29899
ci-image-boot-test: Jenkins Job builder account
ci-image-build: Jenkins Job builder account
Tested-by: Jenkins Job builder account