avformat/oggenc: free buffered page lists while uninitializing the muxer

If the trailer is never writen, there could be buffered pages that would leak.
Reviewed-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
Signed-off-by: James Almer <jamrial@gmail.com>

libavformat/oggenc.c

@@ -740,6 +740,8 @@ static int ogg_write_trailer(AVFormatContext *s)
 
 static void ogg_free(AVFormatContext *s)
 {
+    OGGContext *ogg = s->priv_data;
+    OGGPageList *p = ogg->page_list;
     int i;
 
     for (i = 0; i < s->nb_streams; i++) {
@@ -756,6 +758,13 @@ static void ogg_free(AVFormatContext *s)
         av_freep(&oggstream->header[1]);
         av_freep(&st->priv_data);
     }
+
+    while (p) {
+        OGGPageList *next = p->next;
+        av_free(p);
+        p = next;
+    }
+    ogg->page_list = NULL;
 }
 
 #if CONFIG_OGG_MUXER