[clang] [Clang][LLVM][Coroutines] Prevent __coro_gro from outliving __promise (PR #66706)

[Chuanqi Xu via cfe-commits]

https://github.com/ChuanqiXu9 commented:

Thanks. It looks good if we can add llvm test in llvm/test/Transforms/Coroutines for the new metadata.

https://github.com/llvm/llvm-project/pull/66706