mjpegtools: new package

The mjpegtools programs are a set of tools that can do recording of videos
and playback, simple cut-and-paste editing and the MPEG compression of audio
and video under Linux.

[Peter: license is GPLv2+]
Signed-off-by: Steve Kenton <skenton@ou.edu>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>