[gtk/glyph-cache-fixes] Add missing includes

[Matthias Clasen <matthiasc src gnome org>]

commit 6118dfba747ac7ef82fade52b35f6516920ed513
Author: Matthias Clasen <mclasen redhat com>
Date:   Wed Jul 31 08:04:03 2019 -0400

    Add missing includes

 testsuite/reftests/image-compare.c | 2 ++
 1 file changed, 2 insertions(+)
---
diff --git a/testsuite/reftests/image-compare.c b/testsuite/reftests/image-compare.c
index a69bdeac3f..07bb79e4e0 100644
--- a/testsuite/reftests/image-compare.c
+++ b/testsuite/reftests/image-compare.c
@@ -1,5 +1,7 @@
 #include "config.h"
 
+#include <stdlib.h>
+
 #include "reftest-compare.h"
 
 static char *opt_filename;