oggdec: fix invalid free on error

The read_packet callback passes a pointer to a stack-allocated AVPacket.
Attempting to free it with av_free() makes no sense.
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
(cherry picked from commit b173f5c1)

Conflicts:

	libavformat/oggdec.c
(cherry picked from commit a82401b7284e05e2cf6fb89aeed53738af06a7fd)
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavformat/oggdec.c

@@ -780,7 +780,6 @@ retry:
                                                      10);
         if(side_data == NULL) {
             av_free_packet(pkt);
-            av_free(pkt);
             return AVERROR(ENOMEM);
         }
         AV_WL32(side_data + 4, os->end_trimming);