LockSet:tryAcquireOrBackoff use optional<ref_wrapper<Qutex>>

Replace the previous Qutex** raw pointer with a std::optional.

include/serializedAsynchronousContinuation.h

@@ -107,14 +107,12 @@ public:
 					"executing on wrong ComponentThread");
 			}
 
-			Qutex *firstFailedQutexPtr = nullptr;
+			std::optional<std::reference_wrapper<Qutex>> firstFailedQutexRet;
 			bool deadlockLikely = isDeadlockLikely();
 			bool gridlockLikely = isGridlockLikely();
 
 			if (!serializedContinuation.requiredLocks.tryAcquireOrBackOff(
-				*this,
-				((deadlockLikely || gridlockLikely)
-					? &firstFailedQutexPtr : nullptr)))
+				*this, firstFailedQutexRet))
 			{
 				// Just allow this lockvoker to be dropped from its io_service.
 				allowAwakening();
@@ -122,7 +120,7 @@ public:
 					{ return; }
 
 #ifdef CONFIG_ENABLE_DEBUG_LOCKS
-				Qutex	&firstFailedQutex = *firstFailedQutexPtr;
+				Qutex	&firstFailedQutex = firstFailedQutexRet.value().get();
 				bool isDeadlock = traceContinuationHistoryForDeadlockOn(
 					firstFailedQutex);