[clang] [Clang][Coroutines] Improve GRO handling to better fit scopes and cleanups (PR #66706)

[Bruno Cardoso Lopes via cfe-commits]

bcardosolopes wrote:

Updated the patch to account for failing libcxx tests, and to not change current codegen when GRO allocas are not involved.

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