Merge remote-tracking branch 'remotes/kraxel/tags/pull-vga-20160523-1' into staging

vga: fix CVE-2016-3712 regression, misc virtio-gpu fixes.

# gpg: Signature made Mon 23 May 2016 13:30:26 BST using RSA key ID D3E87138
# gpg: Good signature from "Gerd Hoffmann (work) <[email protected]>"
# gpg:                 aka "Gerd Hoffmann <[email protected]>"
# gpg:                 aka "Gerd Hoffmann (private) <[email protected]>"

* remotes/kraxel/tags/pull-vga-20160523-1:
  vga: add sr_vbe register set
  virtio-gpu: fix ui idx check
  virtio-gpu: use VIRTIO_GPU_MAX_SCANOUTS
  virtio-gpu: check max_outputs only
  virtio-gpu: check max_outputs value
  virtio-vga: propagate on gpu realized error
  virtio-gpu: check early scanout id

Signed-off-by: Peter Maydell <[email protected]>