[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 afraid it is not working. Backend rejects the transformed IR. [godbolt](https://godbolt.org/z/937jzd7PT)

You can reproduce it with
``` bash
opt pr148035_inst_does_not_dominate.ll -passes='cgscc(coro-split),coro-cleanup' | llc
```



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