Change remaining GPLv2 headers to MIT

The files in question are copyright Benjamin Franzke (who agrees),
Intel Corporation, Red Hat and myself.  On behalf of Red Hat,
Richard Fontana says:

   "Therefore, to the extent that Red Hat, Inc. has any copyright
    interest in the files you cited as of this date (compositor-drm.c,
    compositor.c, compositor.h, screenshooter.c in
    http://cgit.freedesktop.org/wayland/wayland-demos/tree/compositor),
    Red Hat hereby elects to apply the CC0 1.0 Universal Public Domain
    Dedication to such copyrighted material.  See:
    http://creativecommons.org/publicdomain/zero/1.0/legalcode .

    Thanks,
    Richard E. Fontana
    Open Source Licensing and Patent Counsel
    Red Hat, Inc."
7 files changed