[llvm] RFC: [Offload] Design for async error handling (PR #155596)

[Ross Brunton via llvm-commits]

RossBrunton wrote:

@jhuber6 From the end user perspective, I'm imagining something like this:

```c++
ol_queue_handle_t Queue;
olCreateQueue(Device, &Queue);
// Enqueue a lot of work to the queue
auto Err = olSyncQueue(Queue);
if (Err && Err->Code == OL_ERRC_QUEUE_ERROR) {
  olGetQueueError(Queue, &Err, nullptr);
  std::cerr << "Error: " << Err.Desc << "\n";
}
```

I'm still not 100% sure how to implement it on AMD/Nvidia. I was going to look into it more if the design looked good.

https://github.com/llvm/llvm-project/pull/155596