[libcxx-commits] [libcxx] [libc++] Add missing xlocale.h include on Apple and FreeBSD (PR #99689)

[Nikolas Klauser via libcxx-commits]

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

We should export this from `locale_base_api.h`. That's what the header is for.

https://github.com/llvm/llvm-project/pull/99689