sched: Fix cpupri build on !CONFIG_SMP

This build bug:

 In file included from kernel/sched.c:1765:
 kernel/sched_rt.c: In function ‘has_pushable_tasks’:
 kernel/sched_rt.c:1069: error: ‘struct rt_rq’ has no member named ‘pushable_tasks’
 kernel/sched_rt.c: In function ‘pick_next_task_rt’:
 kernel/sched_rt.c:1084: error: ‘struct rq’ has no member named ‘post_schedule’

Triggers because both pushable_tasks and post_schedule are
SMP-only fields.

Move pushable_tasks() to the SMP section and #ifdef the post_schedule use.

Cc: Gregory Haskins <ghaskins@novell.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20090729150422.17691.55590.stgit@dev.haskins.net>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

kernel/sched_rt.c

@@ -136,6 +136,11 @@ static void dequeue_pushable_task(struct rq *rq, struct task_struct *p)
 	plist_del(&p->pushable_tasks, &rq->rt.pushable_tasks);
 }
 
+static inline int has_pushable_tasks(struct rq *rq)
+{
+	return !plist_head_empty(&rq->rt.pushable_tasks);
+}
+
 #else
 
 static inline void enqueue_pushable_task(struct rq *rq, struct task_struct *p)
@@ -1064,11 +1069,6 @@ static struct task_struct *_pick_next_task_rt(struct rq *rq)
 	return p;
 }
 
-static inline int has_pushable_tasks(struct rq *rq)
-{
-	return !plist_head_empty(&rq->rt.pushable_tasks);
-}
-
 static struct task_struct *pick_next_task_rt(struct rq *rq)
 {
 	struct task_struct *p = _pick_next_task_rt(rq);
@@ -1077,11 +1077,13 @@ static struct task_struct *pick_next_task_rt(struct rq *rq)
 	if (p)
 		dequeue_pushable_task(rq, p);
 
+#ifdef CONFIG_SMP
 	/*
 	 * We detect this state here so that we can avoid taking the RQ
 	 * lock again later if there is no need to push
 	 */
 	rq->post_schedule = has_pushable_tasks(rq);
+#endif
 
 	return p;
 }