8231472: Clean up Monitor::_safepoint_check usage to Mutex::_safepoint_check

Change Monitor:: to Mutex:: when allocating a Mutex, and in mutexLocker.

Reviewed-by: rehn, dholmes

src/hotspot/share/services/memoryManager.cpp

@@ -178,7 +178,7 @@ GCMemoryManager::GCMemoryManager(const char* name, const char* gc_end_message) :
   _num_collections = 0;
   _last_gc_stat = NULL;
   _last_gc_lock = new Mutex(Mutex::leaf, "_last_gc_lock", true,
-                            Monitor::_safepoint_check_never);
+                            Mutex::_safepoint_check_never);
   _current_gc_stat = NULL;
   _num_gc_threads = 1;
   _notification_enabled = false;