fix a bug in bh queue

Author: TianlongLiang

core/shared/utils/bh_queue.c

@@ -96,14 +96,15 @@ bh_queue_destroy(bh_queue *queue)
 bool
 bh_post_msg2(bh_queue *queue, bh_queue_node *msg)
 {
+    bh_queue_mutex_lock(&queue->queue_lock);
+
     if (queue->cnt >= queue->max) {
         queue->drops++;
         bh_free_msg(msg);
+        bh_queue_mutex_unlock(&queue->queue_lock);
         return false;
     }
 
-    bh_queue_mutex_lock(&queue->queue_lock);
-
     if (queue->cnt == 0) {
         bh_assert(queue->head == NULL);
         bh_assert(queue->tail == NULL);