sched: Consolidate account_system_vtime extern declaration

Just a minor cleanup patch that makes things easier to the following patches.
No functionality change in this patch.

Signed-off-by: Venkatesh Pallipadi <venki@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1286237003-12406-3-git-send-email-venki@google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/include/linux/hardirq.h b/include/linux/hardirq.h
index e37a77c..41367c5 100644
--- a/include/linux/hardirq.h
+++ b/include/linux/hardirq.h
@@ -141,6 +141,8 @@
 static inline void account_system_vtime(struct task_struct *tsk)
 {
 }
+#else
+extern void account_system_vtime(struct task_struct *tsk);
 #endif
 
 #if defined(CONFIG_NO_HZ)