Do not fail fatally if chan atom is too short.

libavformat/mov.c

@@ -2341,7 +2341,7 @@ static int mov_read_elst(MOVContext *c, AVIOContext *pb, MOVAtom atom)
 static int mov_read_chan(MOVContext *c, AVIOContext *pb, MOVAtom atom)
 {
     if (atom.size < 16)
-        return AVERROR_INVALIDDATA;
+        return 0;
     avio_skip(pb, 4);
     ff_mov_read_chan(c->fc, atom.size - 4, c->fc->streams[0]->codec);
     return 0;