We were never reporting the G_IO_HUP event when an end of file was hit
on the websocket channel.

We also didn't report G_IO_ERR when we hit a fatal error processing the
websocket protocol.

The latter in particular meant that the chardev code would not notice
when an eof/error was encountered on the websocket channel, unless the
guest OS happened to trigger a write operation.

This meant that once the first client had quit, the chardev would never
listen to accept a new client.

Fixes launchpad bug 1816819
Acked-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>