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

Fix object interface check macro usage

# gpg: Signature made Thu 21 Mar 2019 11:53:15 GMT
# gpg:                using RSA key BE86EBB415104FDF
# gpg: Good signature from "Daniel P. Berrange <dan@berrange.com>" [full]
# gpg:                 aka "Daniel P. Berrange <berrange@redhat.com>" [full]
# Primary key fingerprint: DAF3 A6FD B26B 6291 2D0E  8E3F BE86 EBB4 1510 4FDF

* remotes/berrange/tags/authz-next-pull-request:
  authz: Use OBJECT_CHECK() on objects

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