message: fix mysql iowait error
diff: @@ -859,7 +859,6 @@ static int swoole_mysql_coro_onRead(swReactor *reactor, swEvent *event)
  return SW_OK;
  }
  client->_defer = 0;
  - client->iowait = SW_MYSQL_CORO_STATUS_READY;
  php_context *sw_current_context = swoole_get_property(zobject, 0);
  ret = coro_resume(sw_current_context, result, &retval);
  sw_zval_free(result);
  