Merge remote-tracking branch 'remotes/kraxel/tags/pull-sdl-20150611-1' into staging

sdl2: fix crash in handle_windowevent() when restoring the screen size

# gpg: Signature made Thu Jun 11 08:57:38 2015 BST 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-sdl-20150611-1:
  sdl2: fix crash in handle_windowevent() when restoring the screen size

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