SocketListener.addSocket

Adds socket to the set of sockets that we try to accept new clients from. The socket must be bound to a local address and listened to.

source_object will be passed out in the various calls to accept to identify this particular source, which is useful if you're listening on multiple addresses and do different things depending on what address is connected to.

The socket will not be automatically closed when the listener is finalized unless the listener held the final reference to the socket. Before GLib 2.42, the socket was automatically closed on finalization of the listener, even if references to it were held elsewhere.