sched: remove old cpu accounting field

remove the old cpu-accounting field from signal_struct, now
that the code is using CFS's stats.

Signed-off-by: Ingo Molnar <mingo@elte.hu>

include/linux/sched.h

@@ -482,7 +482,6 @@ struct signal_struct {
 	 * from jiffies_to_ns(utime + stime) if sched_clock uses something
 	 * other than jiffies.)
 	 */
-	unsigned long sched_time;
 	unsigned long long sum_sched_runtime;
 
 	/*