[clang] Add fine-grained `__has_feature()` cutout (PR #170822)

[via cfe-commits]

j39m wrote:

I'm unable to reproduce the test failure in my checkout. I tried mimicking a subset of `monolithic-linux.sh`, but neither of `check-clang` or `check-clang-tools` produces any failures that I can see.

https://github.com/llvm/llvm-project/pull/170822