oggdec: improve warning message.

Print whether it was a keyframe or a non-keyframe that
was incorrectly marked as the other.
Signed-off-by: Reimar Döffinger <Reimar.Doeffinger@gmx.de>

libavformat/oggdec.c

@@ -582,8 +582,9 @@ static void ogg_validate_keyframe(AVFormatContext *s, int idx, int pstart, int p
     struct ogg_stream *os = ogg->streams + idx;
     if (psize && s->streams[idx]->codec->codec_id == CODEC_ID_THEORA) {
         if (!!(os->pflags & AV_PKT_FLAG_KEY) != !(os->buf[pstart] & 0x40)) {
-            av_log(s, AV_LOG_WARNING, "Broken file, keyframes not correctly marked.\n");
             os->pflags ^= AV_PKT_FLAG_KEY;
+            av_log(s, AV_LOG_WARNING, "Broken file, %skeyframe not correctly marked.\n",
+                   (os->pflags & AV_PKT_FLAG_KEY) ? "" : "non-");
         }
     }
 }