server: increase listen queue to 128

This will allow more than 1 simultaneous client connections to the server
without the possibility of connection refused error.

Signed-off-by: Imran Zaman <imran.zaman@gmail.com>

http://utcc.utoronto.ca/~cks/space/blog/unix/ListenBacklogMeaning
http://stackoverflow.com/questions/19221105/connect-with-unix-domain-socket-and-full-backlog


Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>