[libcxx-commits] [libcxx] [libc++][numeric] Refactor `std::midpoint` tests (PR #175531)

[Nikolas Klauser via libcxx-commits]

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

This isn't just formatting stuff. Again, please separate formatting-only changes from others so it's easier to see what's going on.

https://github.com/llvm/llvm-project/pull/175531