[gegl] buffer: add an include of stdlib.h for abs

[Øyvind Kolås <ok src gnome org>]

commit a99dac2f15639676add8ed30fad35e5052687d66
Author: Øyvind Kolås <pippin gimp org>
Date:   Wed Jul 13 18:47:07 2016 +0200

    buffer: add an include of stdlib.h for abs

 gegl/buffer/gegl-buffer-access.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/gegl/buffer/gegl-buffer-access.c b/gegl/buffer/gegl-buffer-access.c
index d49e6aa..4cbb1cc 100644
--- a/gegl/buffer/gegl-buffer-access.c
+++ b/gegl/buffer/gegl-buffer-access.c
@@ -19,6 +19,7 @@
 
 #include "config.h"
 #include <string.h>
+#include <stdlib.h>
 #include <math.h>
 
 #include <glib-object.h>