message: Improve the overflow tip.
diff: @@ -207,12 +207,9 @@ static int swFactoryProcess_finish(swFactory *factory, swSendData *resp)
  return SW_ERR;
  }
  else if (conn->overflow)
  - {
  - if (serv->send_yield)
  {
  SwooleG.error = SW_ERROR_OUTPUT_BUFFER_OVERFLOW;
  - }
  - else
  + if (!serv->send_yield)
  {
  swoole_error_log(SW_LOG_WARNING, SW_ERROR_OUTPUT_BUFFER_OVERFLOW, "send failed, connection[fd=%d] output buffer has been overflowed.", session_id);
  }
  