Added a spinlock template as well as a thread work pool class.

Also, optimized shader compilation to happen on threads.

core/command_queue_mt.cpp

@@ -111,11 +111,11 @@ CommandQueueMT::CommandQueueMT(bool p_sync) {
 
 	for (int i = 0; i < SYNC_SEMAPHORES; i++) {
 
-		sync_sems[i].sem = Semaphore::create();
+		sync_sems[i].sem = SemaphoreOld::create();
 		sync_sems[i].in_use = false;
 	}
 	if (p_sync)
-		sync = Semaphore::create();
+		sync = SemaphoreOld::create();
 	else
 		sync = NULL;
 }