https://bugs.gentoo.org/721676

From 9ae36d7d5f7420eaacd9644451933512fa13d716 Mon Sep 17 00:00:00 2001
From: sekrit-twc <sekrit-twc@users.noreply.github.com>
Date: Wed, 4 Dec 2019 12:01:26 -0800
Subject: [PATCH] Update matrix3.cpp

---
 src/zimg/colorspace/matrix3.cpp | 1 +
 1 file changed, 1 insertion(+)

--- a/src/zimg/colorspace/matrix3.cpp
+++ b/src/zimg/colorspace/matrix3.cpp
@@ -1,3 +1,4 @@
+#include <cstddef>
 #include "matrix3.h"
 
 namespace zimg {