[libcxx-commits] [libcxx] [libc++] Fix `regex_search` to match `$` alone with `match_default` flag (PR #77256)

[Mark de Wever via libcxx-commits]

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

Thanks looks good, I'd like one more test before approval.

https://github.com/llvm/llvm-project/pull/77256