Merge remote-tracking branch 'remotes/berrange/tags/pull-qio-2017-11-28-1' into staging

Merge qio 2017/11/28 v1

# gpg: Signature made Tue 28 Nov 2017 10:49:08 GMT
# gpg:                using RSA key 0xBE86EBB415104FDF
# gpg: Good signature from "Daniel P. Berrange <dan@berrange.com>"
# gpg:                 aka "Daniel P. Berrange <berrange@redhat.com>"
# Primary key fingerprint: DAF3 A6FD B26B 6291 2D0E  8E3F BE86 EBB4 1510 4FDF

* remotes/berrange/tags/pull-qio-2017-11-28-1:
  sockets: avoid crash when cleaning up sockets for an invalid FD

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>