Description of problem:
When using the -n flag, iostat creates new open file handles while running, and
fails to close them.  One new handle opening /proc/<iostat's-PID>/mountstats per
interval.

     Version-Release number of selected components:
# rpm -q sysstat
sysstat-7.0.0-3.el5
# cat /etc/redhat-release
Red Hat Enterprise Linux Server release 5.1 (Tikanga)
# uname -a
Linux hostname 2.6.18-53.el5 #1 SMP Wed Oct 10 16:34:19 EDT 2007 x86_64


     Steps to Reproduce:
1. Run iostat with the -n flag, and an interval value.  (EG:  iostat -n 1)
2. Use lsof to determine the number of open files for a process.
3. Iostat will eventually crash because of too many open files.
  
     Examples:
1. Start an iostat command running in one terminal window:  iostat -n 1
2. In another terminal window, monitor open file usage with lsof:  lsof -c
/iostat/ | wc
3. Rerunning the lsof command above will return with an ever increasing number
of open files.
4. After 17 minutes and 2 seconds of running, iostat will crash with the error:
 "fopen: Too many open files"

     Output:
# time iostat -n 1 > /dev/null &
[2]     2525
# lsof -c /iostat/ | wc
      22     195    1624
# lsof -c /iostat/ | wc
      38     339    2872
# lsof -c /iostat/ | wc
     259    2328   20110
# lsof -c /iostat/ | wc
     306    2751   23776
# lsof -c /iostat/ | wc
     507    4560   39454
# lsof -c /iostat/ | wc
     959    8628   74710
# fopen: Too many open files

real    17m2.04s
user    0m0.08s
sys     0m0.94s