Commit "9d8256eb virgl: pass whole GL scanout dimensions" missed the
opengl code path for gtk versions >= 3.16.  Update that one too and
fix the build with recent gtk versions.

Reported-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Message-id: 1467876563-1351-1-git-send-email-kraxel@redhat.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>