movenc: Don't write any edit list if the start offset is zero

In these cases, the CTTS flag is set, but no edit list is necessary.
Signed-off-by: Martin Storsjö <martin@martin.st>

libavformat/movenc.c

@@ -1811,8 +1811,7 @@ static int mov_write_trak_tag(AVIOContext *pb, MOVMuxContext *mov,
     ffio_wfourcc(pb, "trak");
     mov_write_tkhd_tag(pb, mov, track, st);
     if (track->start_dts != AV_NOPTS_VALUE &&
-        (track->mode == MODE_PSP || track->flags & MOV_TRACK_CTTS ||
-        track->start_dts || is_clcp_track(track))) {
+        (track->mode == MODE_PSP || track->start_dts || is_clcp_track(track))) {
         if (mov->use_editlist)
             mov_write_edts_tag(pb, mov, track);  // PSP Movies require edts box
         else if ((track->entry && track->cluster[0].dts) || track->mode == MODE_PSP || is_clcp_track(track))