avcodec/cdxl: use av_freep()

Signed-off-by: Paul B Mahol <onemda@gmail.com>

libavcodec/cdxl.c

@@ -291,7 +291,7 @@ static av_cold int cdxl_decode_end(AVCodecContext *avctx)
 {
     CDXLVideoContext *c = avctx->priv_data;
 
-    av_free(c->new_video);
+    av_freep(&c->new_video);
 
     return 0;
 }