libcxx: Always use clang to compile libcxx
libcxx: Always use clang to compile libcxx

It really does not build with gcc dont force it

Signed-off-by: Khem Raj <729d64b6f67515e258459a5f6d20ec88b2caf8df@gmail.com>

kraj/meta-clang,kraj/meta-clang,kraj/meta-clang