[glick2] Define _GNU_SOURCE so that we get CLONE_NEWNS

[Alexander Larsson <alexl src gnome org>]

commit 66d30fb2ef03d6f7be19085c6f1cb4d99fcaaea3
Author: Alexander Larsson <alexl redhat com>
Date:   Fri Oct 21 08:21:25 2011 +0200

    Define _GNU_SOURCE so that we get CLONE_NEWNS

 session.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/session.c b/session.c
index 8e60c86..55d925a 100644
--- a/session.c
+++ b/session.c
@@ -1,5 +1,7 @@
 #include "config.h"
 
+#define _GNU_SOURCE /* Required for CLONE_NEWNS */
+
 #include <sys/mount.h>
 #include <sys/types.h>
 #include <sys/stat.h>