mp_image: replace rude function with less rude FFmpeg upstream function

This is new, thus a dependency bump is required.

common/av_common.h

@@ -47,8 +47,5 @@ const char *mp_codec_from_av_codec_id(int codec_id);
 void mp_set_avdict(struct AVDictionary **dict, char **kv);
 void mp_avdict_print_unset(struct mp_log *log, int msgl, struct AVDictionary *d);
 int mp_set_avopts(struct mp_log *log, void *avobj, char **kv);
-AVFrameSideData *ffmpeg_garbage(AVFrame *frame,
-                                enum AVFrameSideDataType type,
-                                AVBufferRef *buf);
 
 #endif