Do not print a useless error number if mov header reading fails.

The error string is printed by ffmpeg as for other demuxers.

libavformat/mov.c

@@ -3562,7 +3562,7 @@ static int mov_read_header(AVFormatContext *s)
     if (mov->moov_retry)
         avio_seek(pb, 0, SEEK_SET);
     if ((err = mov_read_default(mov, pb, atom)) < 0) {
-        av_log(s, AV_LOG_ERROR, "error reading header: %d\n", err);
+        av_log(s, AV_LOG_ERROR, "error reading header\n");
         mov_read_close(s);
         return err;
     }