[gnome-screensaver] Fix compiler warning for "exit"

[Javier Jardón <jjardon src gnome org>]

commit c2b0dee8578e168ceeebe2fd4f1a48f3de9356e9
Author: Andre Klapper <a9016009 gmx de>
Date:   Wed Jun 23 11:51:02 2010 +0200

    Fix compiler warning for "exit"

 savers/popsquares.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/savers/popsquares.c b/savers/popsquares.c
index 94bdf7d..f13bfff 100644
--- a/savers/popsquares.c
+++ b/savers/popsquares.c
@@ -21,6 +21,7 @@
 
 #include "config.h"
 
+#include <stdlib.h>
 #include <string.h>
 #include <gdk/gdk.h>
 #include <gdk/gdkx.h>