[llvm-branch-commits] [libcxx] [libc++][modules] Adds module testing. (PR #76246)

[Louis Dionne via llvm-branch-commits]

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

This generally looks good to me, but I have some feedback per our live review! Thanks, this is a great simplification overall.

https://github.com/llvm/llvm-project/pull/76246