message: fix mysql_coro->query failed.
diff: @@ -108,7 +108,6 @@ static void swoole_mysql_coro_onConnect(mysql_client *client TSRMLS_DC);
  static void swoole_mysql_coro_onTimeout(php_context *cxt);
  extern swString *mysql_request_buffer;
  -static int isset_event_callback = 0;
  void swoole_mysql_coro_init(int module_number TSRMLS_DC)
  {
  @@ -318,7 +317,7 @@ static PHP_METHOD(swoole_mysql_coro, connect)
  }
  php_swoole_check_reactor();
  - if (!isset_event_callback)
  + if (!swReactor_handle_isset(SwooleG.main_reactor, PHP_SWOOLE_FD_MYSQL))
  {
  SwooleG.main_reactor->setHandle(SwooleG.main_reactor, PHP_SWOOLE_FD_MYSQL | SW_EVENT_READ, swoole_mysql_coro_onRead);
  SwooleG.main_reactor->setHandle(SwooleG.main_reactor, PHP_SWOOLE_FD_MYSQL | SW_EVENT_WRITE, swoole_mysql_coro_onWrite);
  @@ -453,12 +452,6 @@ static PHP_METHOD(swoole_mysql_coro, query)
  {
  RETURN_FALSE;
  }
  - //add to eventloop
  - if (SwooleG.main_reactor->add(SwooleG.main_reactor, client->fd, PHP_SWOOLE_FD_MYSQL | SW_EVENT_READ) < 0)
  - {
  - swoole_php_fatal_error(E_WARNING, "swoole_event_add failed.");
  - RETURN_FALSE;
  - }
  //send query
  if (SwooleG.main_reactor->write(SwooleG.main_reactor, client->fd, mysql_request_buffer->str, mysql_request_buffer->length) < 0)
  {
  