sched: add CONFIG_SMP consistency

a patch from Henrik Austad did this:

>> Do not declare select_task_rq as part of sched_class when CONFIG_SMP is
>> not set.

Peter observed:

> While a proper cleanup, could you do it by re-arranging the methods so
> as to not create an additional ifdef?

Do not declare select_task_rq and some other methods as part of sched_class
when CONFIG_SMP is not set.

Also gather those methods to avoid CONFIG_SMP mess.

Idea-by: Henrik Austad <henrik.austad@gmail.com>
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Henrik Austad <henrik@austad.us>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

include/linux/sched.h

@@ -897,7 +897,6 @@ struct sched_class {
 	void (*enqueue_task) (struct rq *rq, struct task_struct *p, int wakeup);
 	void (*dequeue_task) (struct rq *rq, struct task_struct *p, int sleep);
 	void (*yield_task) (struct rq *rq);
-	int  (*select_task_rq)(struct task_struct *p, int sync);
 
 	void (*check_preempt_curr) (struct rq *rq, struct task_struct *p, int sync);
 
@@ -905,6 +904,8 @@ struct sched_class {
 	void (*put_prev_task) (struct rq *rq, struct task_struct *p);
 
 #ifdef CONFIG_SMP
+	int  (*select_task_rq)(struct task_struct *p, int sync);
+
 	unsigned long (*load_balance) (struct rq *this_rq, int this_cpu,
 			struct rq *busiest, unsigned long max_load_move,
 			struct sched_domain *sd, enum cpu_idle_type idle,
@@ -916,16 +917,17 @@ struct sched_class {
 	void (*pre_schedule) (struct rq *this_rq, struct task_struct *task);
 	void (*post_schedule) (struct rq *this_rq);
 	void (*task_wake_up) (struct rq *this_rq, struct task_struct *task);
-#endif
 
-	void (*set_curr_task) (struct rq *rq);
-	void (*task_tick) (struct rq *rq, struct task_struct *p, int queued);
-	void (*task_new) (struct rq *rq, struct task_struct *p);
 	void (*set_cpus_allowed)(struct task_struct *p,
 				 const cpumask_t *newmask);
 
 	void (*rq_online)(struct rq *rq);
 	void (*rq_offline)(struct rq *rq);
+#endif
+
+	void (*set_curr_task) (struct rq *rq);
+	void (*task_tick) (struct rq *rq, struct task_struct *p, int queued);
+	void (*task_new) (struct rq *rq, struct task_struct *p);
 
 	void (*switched_from) (struct rq *this_rq, struct task_struct *task,
 			       int running);