[Cin] Correction (for libavcodec usage inside Cinelerra-GG [LONG])

[Andrew Randrianasulu]

I included link to our bugtracker issue #330, but it was not meant to say FFmpeg 
should be absolutely blamed on this - just that my primitive fprintf debugging showed something
like jumping around at seek timestamps (due to cinelerra-GG using different seek method, relative to ffplay/mplayer)

I just hope I not ruined our communication.