According to style(9):
> normally, include <sys/types.h> OR <sys/param.h>, but not both.
(<sys/param.h> already includes <sys/types.h> when LOCORE is not defined).
We have an nitems() macro in the <sys/param.h> header that is
convenient to re-use as it makes things easier to read.
Given that it is available already without adding additional
headers and other parts of libc already use it, extend a bit
more its use.
From
http://www.isc.org/downloads/libbind/
The libbind functions have been separated from the BIND suite as of BIND
9.6.0. Originally from older versions of BIND, they have been continually
maintained and improved but not installed by default with BIND 9. This
standard resolver library contains the same historical functions and
headers included with many Unix operating systems. In fact, most
implementations are based on the same original code.
At present, NetBSD maintains libbind code, now known as "netresolv".