Using Swoole's eventLoopClass

Hello @walkor

What is exactly happening when I set `$eventLoopClass` to `Workerman\Events\Swoole` and use the following in `onMessage`? How come Swoole's coroutines working without issues ?! 🤔

```
$http_worker->onMessage = function ($connection, $request) {
Co\run(function()
{
swoole_coroutine_create(function()
{
Co::sleep(1);
echo "Done 1\n";
});

swoole_coroutine_create(function()
{
Co::sleep(1);
echo "Done 2\n";
});
});

// Send data to client
$connection->send("Hello World");
};
```