avformat/flic: se av_freep() to avoid leaving stale extradata pointer

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavformat/flic.c

@@ -175,7 +175,7 @@ static int flic_read_header(AVFormatContext *s)
         avio_seek(pb, 12, SEEK_SET);
 
         /* send over abbreviated FLIC header chunk */
-        av_free(st->codec->extradata);
+        av_freep(&st->codec->extradata);
         if (ff_alloc_extradata(st->codec, 12))
             return AVERROR(ENOMEM);
         memcpy(st->codec->extradata, header, 12);