A user can still enable SDL with '-sdl' or '-display sdl' but start making the
default display GTK by default.

I'd also like to deprecate the SDL display and remove it in a few releases.
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>
Message-id: 1361367806-4599-9-git-send-email-aliguori@us.ibm.com