[libunwind] libunwind: Remove OS requirements from tests to make them run on more OSes (PR #167642)

[Alexander Richardson via cfe-commits]

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

Relaxing the windows regexes sounds good and it looks like there is just one macos test failure so this should almost be ready to land.

https://github.com/llvm/llvm-project/pull/167642