avformat/mpl2dec: handle files with CRLF linebreaks correctly

Skip the "\r" as normal text. Otherwise it will be the first character
of the string passed to sscanf(), which then fill fail to match the
timestamps.
Signed-off-by: Clément Bœsch <u@pkh.me>

libavformat/mpl2dec.c

@@ -43,7 +43,7 @@ static int mpl2_probe(AVProbeData *p)
         if (sscanf(ptr, "[%"SCNd64"][%"SCNd64"]%c", &start, &end, &c) != 3 &&
             sscanf(ptr, "[%"SCNd64"][]%c",          &start,       &c) != 2)
             return 0;
-        ptr += strcspn(ptr, "\r\n") + 1;
+        ptr += strcspn(ptr, "\n") + 1;
         if (ptr >= ptr_end)
             return 0;
     }