[clang] [Clang][Basic] Enable `__has_feature(cfi)` (PR #151348)

[Peter Collingbourne via cfe-commits]

https://github.com/pcc requested changes to this pull request.

cc @fmayer 

We have been trying to break `__has_feature(undefined_behavior_sanitizer)` into fine grained checks (#148310). If we have `__has_feature(cfi)`mean CFI || KCFI that is sort of going in the opposite direction. Let's take some time to think about whether it is a good idea to combine them like this.

https://github.com/llvm/llvm-project/pull/151348