[llvm] [Offload] `olLaunchHostFunction` (PR #152482)

[Joseph Huber via llvm-commits]

================
@@ -1063,6 +1063,20 @@ struct AMDGPUStreamTy {
   /// Indicate to spread data transfers across all available SDMAs
   bool UseMultipleSdmaEngines;
 
+  /// Wrapper function for implementing host callbacks
+  static void CallbackWrapper(AMDGPUSignalTy *InputSignal,
+                              AMDGPUSignalTy *OutputSignal,
+                              void (*Callback)(void *), void *UserData) {
+    if (InputSignal)
+      if (auto Err = InputSignal->wait())
+        // Wait shouldn't report an error
+        reportFatalInternalError(std::move(Err));
----------------
jhuber6 wrote:

```suggestion
    // The wait call will not error in this context.
    if (InputSignal) {
      if (auto Err = InputSignal->wait())
        reportFatalInternalError(std::move(Err));
    }
```

https://github.com/llvm/llvm-project/pull/152482