[libcxx-commits] [libcxx] [libc++] Remove a few __has_foo defines in __config (PR #90511)

[Nikolas Klauser via libcxx-commits]

https://github.com/philnik777 approved this pull request.

LGTM with `__has_feature` and `__has_extension` added (until we switch to GCC 14). Maybe add a TODO for that.

https://github.com/llvm/llvm-project/pull/90511