main after group_leader dead.
The ac_utime should be calculated as the sum of the signal->utime
and utime of the thread dies last. The ac_stime should be done also.

   ---- do_acct_process() in kernel/acct.c:
   jiffies = cputime_to_jiffies(cputime_add(current->group_leader->utime,
                                            current->signal->utime));
   ac.ac_utime = encode_comp_t(jiffies_to_AHZ(jiffies));
   jiffies = cputime_to_jiffies(cputime_add(current->group_leader->stime,
                                            current->signal->stime));
   ac.ac_stime = encode_comp_t(jiffies_to_AHZ(jiffies));
   ----

The part of the minflt/majflt calculation has same problem.
This patch solves those problems, I think.

Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>