Merge remote-tracking branch 'remotes/kraxel/tags/pull-vga-20170213-1' into staging

vga: bugfixes for cirrus and virtio-gpu

# gpg: Signature made Mon 13 Feb 2017 08:14:47 GMT
# gpg:                using RSA key 0x4CB6D8EED3E87138
# gpg: Good signature from "Gerd Hoffmann (work) <kraxel@redhat.com>"
# gpg:                 aka "Gerd Hoffmann <gerd@kraxel.org>"
# gpg:                 aka "Gerd Hoffmann (private) <kraxel@gmail.com>"
# Primary key fingerprint: A032 8CFF B93A 17A7 9901  FE7D 4CB6 D8EE D3E8 7138

* remotes/kraxel/tags/pull-vga-20170213-1:
  Revert "cirrus: allow zero source pitch in pattern fill rops"
  cirrus: fix patterncopy checks
  cirrus: replace debug printf with trace points
  vga: replace debug printf with trace points
  virtio-gpu: fix resource leak in virgl_cmd_resource_unref
  virtio-gpu: fix memory leak in set scanout

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