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

[Louis Dionne via libcxx-commits]

ldionne wrote:

Even with `export *` in `locale_base_api.h`, we are unable to fix this issue from `locale_base_api.h`. I don't know why that is the case, but I would like to merge this patch so as to make libc++ 19 compatible with a modularized SDK while we spend some cycles cleaning up the `<locale>` story in parallel.

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