ffplay: use seek per time for ogg by default

Fixes Ticket2383

Reviewed-by: Marton Balint <cus@passwd.hu>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

ffplay.c

@@ -2730,7 +2730,7 @@ static int read_thread(void *arg)
         ic->pb->eof_reached = 0; // FIXME hack, ffplay maybe should not use url_feof() to test for the end
 
     if (seek_by_bytes < 0)
-        seek_by_bytes = !!(ic->iformat->flags & AVFMT_TS_DISCONT);
+        seek_by_bytes = !!(ic->iformat->flags & AVFMT_TS_DISCONT) && strcmp("ogg", ic->iformat->name);
 
     is->max_frame_duration = (ic->iformat->flags & AVFMT_TS_DISCONT) ? 10.0 : 3600.0;