SWDEV-555347 - Remove lock contention in async events loop (#878)

* SWDEV-555347 - Remove lock contention in async events loop

* SWDEV-555347 - Introduce Pool of AsyncEventItems

* create generic mempool for AsyncEventItem

* Use BaseShared allocate and free for async event pool

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Co-authored-by: Rahul Manocha <rmanocha@amd.com>

projects/clr/rocclr/platform/commandqueue.cpp

@@ -168,6 +168,7 @@ void HostQueue::finish(bool cpu_wait) {
 
     command = getLastQueuedCommand(true);
     if (command == nullptr) {
+      ClPrint(LOG_DEBUG, LOG_CMD, "No command awaiting completion on host");
       return;
     }
     // Force blocking wait if requested. That allows to avoid a build up of unreleased CPU commands