Reorder mutex enter / vmaccess, add XX flag check

Signed-off-by: Jack Lu <Jack.S.Lu@ibm.com>

Author: fengxue-IS

runtime/vm/ContinuationHelpers.cpp

@@ -858,10 +858,16 @@ takeVirtualThreadListToUnblock(J9VMThread *currentThread, J9JavaVM *vm)
 	jobject result = NULL;
 	J9InternalVMFunctions const * const vmFuncs = vm->internalVMFunctions;
 
+	if (J9_ARE_ANY_BITS_SET(vm->extendedRuntimeFlags3, J9_EXTENDED_RUNTIME3_YIELD_PINNED_CONTINUATION)
+	|| (NULL == vm->blockedContinuations)
+	) {
+		return NULL;
+	}
+
+	omrthread_monitor_enter(vm->blockedVirtualThreadsMutex);
 	vmFuncs->internalEnterVMFromJNI(currentThread);
 	while (NULL == unblockedList) {
 		if (NULL != vm->blockedContinuations) {
-			omrthread_monitor_enter(vm->blockedVirtualThreadsMutex);
 restart:
 			J9VMContinuation *listHead = vm->blockedContinuations;
 			J9VMContinuation *next = NULL;