socket has no attribute 'AF_UNIX' on windows
socket has no attribute 'AF_UNIX' on windows

We should test if socket has such attribute or not.

Change-Id: I9e540b1304ec5c58e9844ff73fd5646f96242ded
Reviewed-on: http://review.couchbase.org/14043
Tested-by: Bin Cui <ed18693fff32c00e22495f4877a3b901bed09041@gmail.com>
Reviewed-by: Steve Yen <ef850f73f7832052d3c6d9b5ddd3a1716d9a57f1@gmail.com>

jimwwalker/ep-engine,hisundar/ep-engine,daverigby/kv_engine,hisundar/ep-engine,abhinavdangeti/ep-engine,abhinavdangeti/ep-engine,hisundar/ep-engine,daverigby/kv_engine,membase/ep-engine,daverigby/ep-engine,teligent-ru/ep-engine,sriganes/ep-engine,daverigby/kv_engine,teligent-ru/ep-engine,jimwwalker/ep-engine,couchbase/ep-engine,jimwwalker/ep-engine,membase/ep-engine,owendCB/ep-engine,sriganes/ep-engine,couchbase/ep-engine,sriganes/ep-engine,daverigby/ep-engine,abhinavdangeti/ep-engine,sriganes/ep-engine,teligent-ru/ep-engine,abhinavdangeti/ep-engine,jimwwalker/ep-engine,membase/ep-engine,couchbase/ep-engine,daverigby/kv_engine,hisundar/ep-engine,membase/ep-engine,teligent-ru/ep-engine,abhinavdangeti/ep-engine,daverigby/ep-engine,owendCB/ep-engine,owendCB/ep-engine,owendCB/ep-engine,daverigby/ep-engine,couchbase/ep-engine