[libcxx-commits] [libcxx] [libc++][NFC] Remove availability annotations which can never be triggered (PR #69226)

[Louis Dionne via libcxx-commits]

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

I think this makes sense and is a nice cleanup. However, we should update the whole codebase consistently.

https://github.com/llvm/llvm-project/pull/69226