Ignore Ogg streams of unknown type but keep track of them

This fixes an issue when there is an Ogg stream in the file that is in a
type unknown to VLC it would forget about this stream ever existing and
therefore putting out errors whenever it encountered a new page with the
forgotten stream serial number:

    ogg demux error: Broken Ogg stream (serialno) mismatch
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

modules/demux/ogg.c

@@ -2017,8 +2017,6 @@ static int Ogg_FindLogicalStreams( demux_t *p_demux )
                 {
                     msg_Dbg( p_demux, "stream %d is of unknown type",
                              p_ogg->i_streams-1 );
-                    FREENULL( p_stream );
-                    p_ogg->i_streams--;
                 }
 
                 /* we'll need to get all headers */