avformat/avidec: remove warning about deprecated declarations

Signed-off-by: James Almer <jamrial@gmail.com>

libavformat/avidec.c

@@ -605,7 +605,11 @@ static int avi_read_header(AVFormatContext *s)
                 ast = s->streams[0]->priv_data;
                 av_freep(&s->streams[0]->codecpar->extradata);
                 av_freep(&s->streams[0]->codecpar);
+#if FF_API_LAVF_AVCTX
+FF_DISABLE_DEPRECATION_WARNINGS
                 av_freep(&s->streams[0]->codec);
+FF_ENABLE_DEPRECATION_WARNINGS
+#endif
                 if (s->streams[0]->info)
                     av_freep(&s->streams[0]->info->duration_error);
                 av_freep(&s->streams[0]->info);