[llvm] coro: Do not capture pointer locals that have no provenance (PR #223321)

[Chuanqi Xu via llvm-commits]

ChuanqiXu9 wrote:

What's the motivation?

This looks not correct. e.g., 

```
void *saved_address = nullptr;

bool save_and_check_address(void * captures(address) addr) {
     if (!saved_address) {
          saved_address = addr;
     }
     return saved_address == addr;
}
```

```
coro_ty coroutine() {
     %a = alloca ...

      for (...) {
           lifetime.start(%a)
           save_and_check_address(%a)
           lifetime.end

           co_await
      }
}
```

then %a may not be moved to the frame in this patch. Theh the address of `a` may be different in this patch vs before.



https://github.com/llvm/llvm-project/pull/223321