avfilter/vf_pixdesctest: use av_malloc_array()

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

libavfilter/vf_pixdesctest.c

@@ -47,7 +47,7 @@ static int config_props(AVFilterLink *inlink)
     priv->pix_desc = av_pix_fmt_desc_get(inlink->format);
 
     av_freep(&priv->line);
-    if (!(priv->line = av_malloc(sizeof(*priv->line) * inlink->w)))
+    if (!(priv->line = av_malloc_array(sizeof(*priv->line), inlink->w)))
         return AVERROR(ENOMEM);
 
     return 0;