LP#1533043 -- aufs hangs when using docker containers

[Andy Whitcroft]

We have reports of docker container hangs on aufs.  This has been tracked
back to a lack of signal handing in XINO handling in aufs.  Following this
email are four patches: two for trusty, trusty/lts-backport-utopic, and
vivid; and two for wily.  Xenial already has these fixes applied via an
AUFS update.

Proposing for SRU to trusty, trusty/lts-backport-utopic, vivid, and wily.