avcodec/nuv: Fix 'libavcodec/nuv.c:83:19: warning: passing argument 3 of av_image_copy from incompatible pointer type'

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/nuv.c

@@ -79,7 +79,7 @@ static void copy_frame(AVFrame *f, const uint8_t *src, int width, int height)
     int src_linesize[4];
     av_image_fill_arrays(src_data, src_linesize, src,
                          f->format, width, height, 1);
-    av_image_copy(f->data, f->linesize, src_data, src_linesize,
+    av_image_copy(f->data, f->linesize, (const uint8_t **)src_data, src_linesize,
                   f->format, width, height);
 }