- simplifying OpenDML AVI handling.
* adding code to skip over JUNK. It turns out that video editing
software uses junk to resize ix## chunks without actually
scrubbing the data. That trips up our packet extraction
code since it recognizes ix## entries as "packets". Basically
we have to skip over JUNK chunks for exactly the same reason
we have to skip over ix## entries.
Originally committed as revision 3378 to svn://svn.ffmpeg.org/ffmpeg/trunk