Merge remote-tracking branch 'remotes/berrange/tags/pull-io-next-2016-03-15-1' into...

Merge I/O fixes

# gpg: Signature made Tue 15 Mar 2016 14:42:43 GMT using RSA key ID 15104FDF
# gpg: Good signature from "Daniel P. Berrange <dan@berrange.com>"
# gpg:                 aka "Daniel P. Berrange <berrange@redhat.com>"

* remotes/berrange/tags/pull-io-next-2016-03-15-1:
  io: stronger check for support for IPv4/6

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