Merge remote-tracking branch 'remotes/berrange/tags/qio-next-pull-request' into staging

Merge qio 2018-06-28 v3

Misc bug fixes for sockets channels

# gpg: Signature made Thu 28 Jun 2018 13:37:35 BST
# gpg:                using RSA key BE86EBB415104FDF
# 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/qio-next-pull-request:
  Delete AF_UNIX socket after close
  socket: don't free msgfds if error equals EAGAIN

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