sched: Wrap the 'cfs_rq->nr_spread_over' field with CONFIG_SCHED_DEBUG

cfs_rq->nr_spread_over is only used when CONFIG_SCHED_DEBUG is set.
So wrap it with CONFIG_SCHED_DEBUG.
Signed-off-by: Rakib Mullick <rakib.mullick@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1304528026.15681.3.camel@localhost.localdomainSigned-off-by: Ingo Molnar <mingo@elte.hu>

kernel/sched.c

@@ -328,7 +328,9 @@ struct cfs_rq {
 	 */
 	struct sched_entity *curr, *next, *last, *skip;
 
+#ifdef	CONFIG_SCHED_DEBUG
 	unsigned int nr_spread_over;
+#endif
 
 #ifdef CONFIG_FAIR_GROUP_SCHED
 	struct rq *rq;	/* cpu runqueue to which this cfs_rq is attached */