[libcxx-commits] [libcxx] [libc++] In `<format>`, use availability macro if including `<locale>` (PR #99274)

[Louis Dionne via libcxx-commits]

ldionne wrote:

Is this still really required, since we don't actually issue an error anymore when including `<locale>` without support for localization?

https://github.com/llvm/llvm-project/pull/99274