http_client: release the socket even if it was disconnected
http_client: release the socket even if it was disconnected

We may have closed it, but not yet released.  Check `!IsReleased()`
instead of `IsConnected()`.

CM4all/beng-proxy,CM4all/beng-proxy,CM4all/beng-proxy,CM4all/beng-proxy,CM4all/beng-proxy,CM4all/beng-proxy