Ignore timeout error when receiving message from sockect
Ignore timeout error when receiving message from sockect

When the clientchannel's receiver thread had crashed with
timeout error. the upside main procedure will contine with-
out any notifications,it may get stocked when no thread can
handle the messages later on.

this change just fix this situation by ignore the timeout
exception, maybe it's a arbitary decision and have a widely
effect.

I will abandon this change if better solution can provide

Change-Id: Ie6058c9b9ffeac7c9af8b3ca9f40ea2b3c940ec2
Closes-Bug: #1623286

openstack/oslo.privsep