Merge remote-tracking branch 'remotes/kraxel/tags/pull-vga-20160301-1' into staging

vga: minor cirrus/qxl bugfixes.

# gpg: Signature made Tue 01 Mar 2016 07:16:22 GMT using RSA key ID D3E87138
# 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>"

* remotes/kraxel/tags/pull-vga-20160301-1:
  qxl: lock current_async update in qxl_soft_reset
  cirrus_vga: fix off-by-one in blit_region_is_unsafe

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