sched: isolate SMP balancing code a bit more

At the moment, a lot of load balancing code that is irrelevant to non
SMP systems gets included during non SMP builds.

This patch addresses this issue and reduces the binary size on non
SMP systems:

   text    data     bss     dec     hex filename
  10983      28    1192   12203    2fab sched.o.before
  10739      28    1192   11959    2eb7 sched.o.after

Signed-off-by: Peter Williams <pwil3058@bigpond.net.au>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/sched_idletask.c b/kernel/sched_idletask.c
index 586b06c..bf9c25c 100644
--- a/kernel/sched_idletask.c
+++ b/kernel/sched_idletask.c
@@ -37,6 +37,7 @@
 {
 }
 
+#ifdef CONFIG_SMP
 static unsigned long
 load_balance_idle(struct rq *this_rq, int this_cpu, struct rq *busiest,
 		  unsigned long max_load_move,
@@ -52,6 +53,7 @@
 {
 	return 0;
 }
+#endif
 
 static void task_tick_idle(struct rq *rq, struct task_struct *curr)
 {
@@ -76,8 +78,10 @@
 	.pick_next_task		= pick_next_task_idle,
 	.put_prev_task		= put_prev_task_idle,
 
+#ifdef CONFIG_SMP
 	.load_balance		= load_balance_idle,
 	.move_one_task		= move_one_task_idle,
+#endif
 
 	.set_curr_task          = set_curr_task_idle,
 	.task_tick		= task_tick_idle,