[clang] [Clang] __has_builtin should return false for aux triple builtins (PR #121839)

[Artem Belevich via cfe-commits]

Artem-B wrote:

This breaks CUDA compilation on ARM, because `__has_builtin()` now returns false for the host-side builtins and that causes some clang headers on ARM to try defining their own replacement for the builtin they consider to be missing, but which is actually still there: https://godbolt.org/z/v9qffds1Y

https://github.com/llvm/llvm-project/blob/285009f202ca8bfcc6b607eba0e919867559e725/clang/lib/Headers/arm_acle.h#L44-L48


https://github.com/llvm/llvm-project/pull/121839