bin/57315: "iostat interval count" doesn't work as expected on NetBSD 9.3

[nan%chinadtrace.org@localhost]

>Number:         57315
>Category:       bin
>Synopsis:       "iostat interval count" doesn't work as expected on NetBSD 9.3
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    bin-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri Mar 31 09:25:00 +0000 2023
>Originator:     Nan Xiao
>Release:        9.3
>Organization:
>Environment:
NetBSD localhost 9.3 NetBSD 9.3 (GENERIC) #0: Thu Aug  4 15:30:37 UTC 2022  mkrepro%mkrepro.NetBSD.org@localhost:/usr/src/sys/arch/amd64/compile/GENERIC amd64
>Description:
On NetBSD 9.3, "iostat interval count" doesn't work as expected, e.g.:

$ iostat 1 4
      tty              wd0               dk0               dk1               cd0             CPU
 tin  tout  KB/t  t/s  MB/s   KB/t  t/s  MB/s   KB/t  t/s  MB/s   KB/t  t/s  MB/s  us ni sy in id
   0    20 13.79   12 0.167  13.83   12 0.167  1.250    0 0.000  0.000    0 0.000   0  0  0  0 99
   0   293 0.000    0 0.000  0.000    0 0.000  0.000    0 0.000  0.000    0 0.000   0  0  0  0 100
   0    99 0.000    0 0.000  0.000    0 0.000  0.000    0 0.000  0.000    0 0.000   0  0  0  0 100
   0    99 16.00    0 0.000  16.00    0 0.000  0.000    0 0.000  0.000    0 0.000   0  0  0  0 100
   0    99 0.000    0 0.000  0.000    0 0.000  0.000    0 0.000  0.000    0 0.000   0  0  0  0 100
   0    99 0.000    0 0.000  0.000    0 0.000  0.000    0 0.000  0.000    0 0.000   0  0  0  0 100
......

I specify count as 4, but it doesn't take effect.
>How-To-Repeat:

>Fix:
Maybe NetBSD 9 should include this commit: https://github.com/NetBSD/src/commit/b91433085cf4ab7e5f1e7c15872fd716f10c4177