message: fix mysql_coro crash.
diff: @@ -1173,6 +1173,8 @@ static void swoole_mysql_coro_onConnect(mysql_client *client TSRMLS_DC)
  ZVAL_BOOL(result, 1);
  }
  + client->cid = 0;
  +
  php_context *sw_current_context = swoole_get_property(zobject, 0);
  int ret = coro_resume(sw_current_context, result, &retval);
  sw_zval_ptr_dtor(&result);
  