Improve socket shutdown codes.
Improve socket shutdown codes.

swoole/swoole-src,LinkedDestiny/swoole-src,swoole/swoole-src,LinkedDestiny/swoole-src,LinkedDestiny/swoole-src,swoole/swoole-src,swoole/swoole-src,LinkedDestiny/swoole-src,LinkedDestiny/swoole-src,swoole/swoole-src,LinkedDestiny/swoole-src,swoole/swoole-src,swoole/swoole-src,LinkedDestiny/swoole-src