avcodec/jpeg2000dec: Free packed_headers

Fixes: memleak
Fixes: 21784/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_JPEG2000_fuzzer-565256551058636

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Reviewed-by: Gautam Ramakrishnan <gautamramk@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/jpeg2000dec.c

@@ -2014,6 +2014,8 @@ static void jpeg2000_dec_cleanup(Jpeg2000DecoderContext *s)
                 ff_jpeg2000_cleanup(comp, codsty);
             }
             av_freep(&s->tile[tileno].comp);
+            av_freep(&s->tile[tileno].packed_headers);
+            s->tile[tileno].packed_headers_size = 0;
         }
     }
     av_freep(&s->tile);