gtk: fix memory leak, add pause key support.

# gpg: Signature made Wed 15 Oct 2014 11:30:39 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-gtk-20141015-1:
  gtk: add support for the Pause key
  gtk.c: Fix memory leak in gd_set_keycode_type()

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