fix that mysqld aborts on exit if an open handlersocket connection remains

plugin/handler_socket/handlersocket/database.cpp

@@ -344,7 +344,7 @@ void
 dbcontext::term_thread()
 {
   DBG_THR(fprintf(stderr, "HNDSOCK thread end %p\n", thd));
-  unlock_tables_if();
+  close_tables_if();
   my_pthread_setspecific_ptr(THR_THD, 0);
   {
     pthread_mutex_lock(&LOCK_thread_count);