Async: Drop-in SyncCancelerForAsyncWork without execUncancelableSegment*

We're doing this to prep for the coro port

commonLibs/attachmentSupport/stimulusProducer.cpp

@@ -91,10 +91,7 @@ void StimulusProducer::destroyAttachedStimulusBuffer(
 
 void StimulusProducer::stop()
 {
-	{
-		sscl::SpinLock::Guard lock(shouldContinueLock);
-		shouldContinue = false;
-	}
+	(void)stimulusProducerCanceler.requestStop();
 
 	// Cancel timer immediately
 	timer.cancel();
@@ -105,7 +102,7 @@ void StimulusProducer::stop()
 
 void StimulusProducer::scheduleNextTimeout(int delayMs)
 {
-	if (!shouldContinue)
+	if (stimulusProducerCanceler.isCancellationRequestedUnlocked())
 		{ return; }
 
 	// Schedule the next timeout using the provided delay
@@ -131,8 +128,8 @@ void StimulusProducer::onTimeout(const boost::system::error_code& error)
 		return;
 	}
 
-	sscl::SpinLock::Guard lock(shouldContinueLock);
-	if (!shouldContinue)
+	sscl::SpinLock::Guard guard(stimulusProducerCanceler.s.lock);
+	if (stimulusProducerCanceler.isCancellationRequestedUnlocked())
 		{ return; }
 
 	/**	EXPLANATION: