fix building of mjpegtools with gcc-4.3
http://bugs.gentoo.org/attachment.cgi?id=145622 it was written by Ryan Hill
Also found in the mjpegtools tracker: https://sourceforge.net/tracker/?func=detail&atid=305776&aid=1947059&group_id=5776
Authored by: waldviertler 2008-05-10
Parent: [r3221]
Child: [r3223]
