[clang] [llvm] [Coroutines] Replace struct alloca frame with byte array and ptradd (PR #178359)

[Chuanqi Xu via cfe-commits]

ChuanqiXu9 wrote:

I feel it is not good to land it directly when there is a reviewer has a question. I think it is better to to ping me and say "Or I'd like to land it in few days (or one week) if no more comments come in". 

CC @nikic as the global maintainer. Do you think my above suggestion makes sense?

https://github.com/llvm/llvm-project/pull/178359