dealloc mutex and cond in msg_queue

lib/include/srslte/common/msg_queue.h

@@ -56,6 +56,9 @@ public:
 
   ~msg_queue()
   {
+    pthread_mutex_destroy(&mutex);
+    pthread_cond_destroy(&not_empty);
+    pthread_cond_destroy(&not_full);
     delete [] buf;
   }