multilib.conf: Add llvm-project-source recipe to NON_MULTILIB_RECIPES

llvm sourcebase is large and like gcc, it reuses same source tree to
build all recipes using clang+llvm sourcebase

(From OE-Core rev: f5dfd524e9f516ea4be72eb8348acb9b31b64a49)

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/conf/multilib.conf

@@ -25,4 +25,4 @@ APT_ARGS:append = " -o Dpkg::Options::=--force-confnew -o Dpkg::Options::=--forc
 
 # These recipes don't need multilib variants, the ${BPN} PROVIDES/RPROVIDES
 # ${MLPREFIX}${BPN}
-NON_MULTILIB_RECIPES = "grub grub-efi make-mod-scripts ovmf u-boot gcc-source"
+NON_MULTILIB_RECIPES = "grub grub-efi make-mod-scripts ovmf u-boot gcc-source llvm-project-source"