Fix the logic for falling back to a non-abstract unix-domain socket
Fix the logic for falling back to a non-abstract unix-domain socket

The code to check for whether bind_to_abstract_socket was failing due
to EADDRINUSE was incorrectly checking the return value instead of
errno so it presumably wouldn't work.

clutter-project/clayland,clutter-project/clayland,clutter-project/clayland,ybakos/clayland,ybakos/clayland