[cheese] Fix another missing stdlib.h include

[David King <davidk src gnome org>]

commit 92c0591ec76568ba5c5f81d1bd7681834a8cc3a9
Author: David King <amigadave amigadave com>
Date:   Mon Sep 3 21:16:38 2012 +0100

    Fix another missing stdlib.h include
    
    For EXIT_FAILURE.

 tests/test-libcheese-gtk.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/tests/test-libcheese-gtk.c b/tests/test-libcheese-gtk.c
index c862942..a90d276 100644
--- a/tests/test-libcheese-gtk.c
+++ b/tests/test-libcheese-gtk.c
@@ -19,6 +19,8 @@
 
 #include "cheese-config.h"
 
+#include <stdlib.h>
+
 #include <glib/gi18n.h>
 #include <gtk/gtk.h>
 #include <gst/gst.h>