[llvm-branch-commits] [libcxx] release/19.x: [libcxx] don't `#include <cwchar>` if wide chars aren't enabled (#99911) (PR #106788)

[Ties Stuij via llvm-branch-commits]

https://github.com/stuij approved this pull request.

Yup, makes sense to cherry-pick.

https://github.com/llvm/llvm-project/pull/106788