fix mistake made in merge

Author: dgrove-oss

src/queue.c

@@ -818,6 +818,7 @@ _dispatch_root_queues_init_workq(void)
 			pthread_workqueue_t pwq = NULL;
 			dispatch_root_queue_context_t qc;
 			qc = &_dispatch_root_queue_contexts[i];
+#if DISPATCH_USE_LEGACY_WORKQUEUE_FALLBACK
 			if (!disable_wq && qc->dgq_wq_priority != WORKQ_PRIO_INVALID) {
 				r = pthread_workqueue_attr_setqueuepriority_np(&pwq_attr,
 						qc->dgq_wq_priority);