avformat/avidec: Remove ancient assert

This assert can with crafted files fail, a warning is already printed
for this case.

Fixes assertion failure
Fixes:1/assert.avi
Found-by: 连一汉 <lianyihan@360.cn>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavformat/avidec.c

@@ -1857,7 +1857,6 @@ static int avi_read_seek(AVFormatContext *s, int stream_index,
             continue;
 
 //        av_assert1(st2->codecpar->block_align);
-        av_assert0(fabs(av_q2d(st2->time_base) - ast2->scale / (double)ast2->rate) < av_q2d(st2->time_base) * 0.00000001);
         index = av_index_search_timestamp(st2,
                                           av_rescale_q(timestamp,
                                                        st->time_base,