avformat/oggdec: reset end_trimming in ogg_reset()

Fixes the output when seeking back to the start
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavformat/oggdec.c

@@ -142,6 +142,7 @@ static int ogg_reset(AVFormatContext *s)
         if (start_pos <= s->data_offset) {
             os->lastpts = 0;
         }
+        os->end_trimming = 0;
     }
 
     ogg->page_pos = -1;