[llvm] [Offload] Make olLaunchKernel test thread safe (PR #149497)

[Ross Brunton via llvm-commits]

================
@@ -2302,8 +2304,11 @@ struct AMDGPUDeviceTy : public GenericDeviceTy, AMDGenericDeviceTy {
     // Once the stream is synchronized, return it to stream pool and reset
     // AsyncInfo. This is to make sure the synchronization only works for its
     // own tasks.
-    AsyncInfo.Queue = nullptr;
-    return AMDGPUStreamManager.returnResource(Stream);
+    if (RemoveQueue) {
----------------
RossBrunton wrote:

@jhuber6 Can you look at this again? I understand that resource management is supposed to be cheap, but there is still a issue with having the queue be in an uninitialised state for a brief period of time in `olWaitQueue`.

https://github.com/llvm/llvm-project/pull/149497