[libcxx-commits] [libcxx] [llvm] [libc++] Deprecate and remove meaningless `<cxxx>` headers (PR #111615)

[Nikolas Klauser via libcxx-commits]

https://github.com/philnik777 requested changes to this pull request.

We could also consider removing most of the headers as a DR. Most of these headers are likely almost never used in the wild except for `<ciso646>` (as our missing `<cstdalign>` shows). @ldionne @jwakely @STL any thoughts?

https://github.com/llvm/llvm-project/pull/111615