[llvm] [Coroutines] fix coroutines + std::unique_ptr with async exceptions validation errors (PR #149691)

[Weibo He via llvm-commits]

https://github.com/NewSigma commented:

I'm reading your patch carefully and noticed you did not split `llvm.seh.scope.begin` into resume/destroy functions? I suspect that `unhandled_exception` would not be invoked if an exception were thrown within the resume/destroy function.

https://github.com/llvm/llvm-project/pull/149691