sched: track cfs_rq->curr on !group-scheduling too

Noticed by Roman Zippel: use cfs_rq->curr in the !group-scheduling
case too. Small micro-optimization and cleanup effect:

   text    data     bss     dec     hex filename
   36269    3482      24   39775    9b5f sched.o.before
   36177    3486      24   39687    9b07 sched.o.after

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/kernel/sched.c b/kernel/sched.c
index f6a8106..3209e2c 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -189,11 +189,11 @@
 	struct rb_root tasks_timeline;
 	struct rb_node *rb_leftmost;
 	struct rb_node *rb_load_balance_curr;
-#ifdef CONFIG_FAIR_GROUP_SCHED
 	/* 'curr' points to currently running entity on this cfs_rq.
 	 * It is set to NULL otherwise (i.e when none are currently running).
 	 */
 	struct sched_entity *curr;
+#ifdef CONFIG_FAIR_GROUP_SCHED
 	struct rq *rq;	/* cpu runqueue to which this cfs_rq is attached */
 
 	/* leaf cfs_rqs are those that hold tasks (lowest schedulable entity in