[libcxx-commits] [libcxx] [libc++] Fix shrink_to_fit to swap buffer only when capacity is strictly smaller (PR #127321)

[Nikolas Klauser via libcxx-commits]

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

I think we should add a libc++-specific test to make sure we don't regress on this.

https://github.com/llvm/llvm-project/pull/127321