sched: SCHED_IDLE weight change

Increase the SCHED_IDLE weight from 2 to 3, this gives much more stable
vruntime numbers.

time advanced in 100ms:

 weight=2

 64765.988352
 67012.881408
 88501.412352

 weight=3

 35496.181411
 34130.971298
 35497.411573

Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

kernel/sched.c

@@ -1323,8 +1323,8 @@ static inline void update_load_sub(struct load_weight *lw, unsigned long dec)
  * slice expiry etc.
  */
 
-#define WEIGHT_IDLEPRIO		2
-#define WMULT_IDLEPRIO		(1 << 31)
+#define WEIGHT_IDLEPRIO                3
+#define WMULT_IDLEPRIO         1431655765
 
 /*
  * Nice levels are multiplicative, with a gentle 10% change for every