It was assumed that mesa provides the necessary X11 includes,
but it is not always the case, as it can be configured without x11 support.

Signed-off-by: Alexander Kanavin <alex.kanavin@gmail.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-id: 20190116113751.17177-1-alex.kanavin@gmail.com

[ kraxel: codestyle fix (long line) ]

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>