sched: fix /proc/<PID>/stat stime/utime monotonicity, part 2

Extend Peter's patch to fix accounting issues, by keeping stime
monotonic too.

Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Tested-by: Frans Pop <elendil@planet.nl>
diff --git a/include/linux/sched.h b/include/linux/sched.h
index b0b1fe6..155d743 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1009,7 +1009,7 @@
 	unsigned int rt_priority;
 	cputime_t utime, stime, utimescaled, stimescaled;
 	cputime_t gtime;
-	cputime_t prev_utime;
+	cputime_t prev_utime, prev_stime;
 	unsigned long nvcsw, nivcsw; /* context switch counts */
 	struct timespec start_time; 		/* monotonic time */
 	struct timespec real_start_time;	/* boot based time */