[clang] [libcxx] [Clang][Sema][Coroutines] Make coroutine startup exception-safe (CWG2935) Part2 (PR #179192)

[Louis Dionne via cfe-commits]

https://github.com/ldionne commented:

If Clang agrees that they want to move forward with this warning, the libc++ test changes seem acceptable. I have no opinion on the warning itself, I haven't spent the time to familiarize myself with the question.

https://github.com/llvm/llvm-project/pull/179192