Merge remote-tracking branch 'remotes/awilliam/tags/vfio-fixes-20180823.1' into staging

VFIO fixes 2018-08-23

 - Fix coverity reported issue with use of realpath (Alex Williamson)

 - Cleanup file descriptor in error path (Alex Williamson)

 - Fix postcopy use of new balloon inhibitor (Alex Williamson)

# gpg: Signature made Thu 23 Aug 2018 17:46:41 BST
# gpg:                using RSA key 239B9B6E3BB08B22
# gpg: Good signature from "Alex Williamson <alex.williamson@redhat.com>"
# gpg:                 aka "Alex Williamson <alex@shazbot.org>"
# gpg:                 aka "Alex Williamson <alwillia@redhat.com>"
# gpg:                 aka "Alex Williamson <alex.l.williamson@gmail.com>"
# Primary key fingerprint: 42F6 C04E 540B D1A9 9E7B  8A90 239B 9B6E 3BB0 8B22

* remotes/awilliam/tags/vfio-fixes-20180823.1:
  postcopy: Synchronize usage of the balloon inhibitor
  vfio/pci: Fix failure to close file descriptor on error
  vfio/pci: Handle subsystem realpath() returning NULL

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