[clang] [clang][Sema] Don't warn for implicit uses of builtins in system headers (PR #138205)

[Artem Belevich via cfe-commits]

Artem-B wrote:

OK. This makes sense. 

> sorry this change is so drawn out :)

What matters is that you're making progress, and I appreciate your work on getting this issue sorted out the right way. 


https://github.com/llvm/llvm-project/pull/138205