Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

MFC r240954:
Teach getent(1) to look up a hostname and find IPv6 addresses.

PR: bin/161548
Submitted by: matthew

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Change how getent utmpx works.

- Always require active, log or lastlogin to be provided.
- Allow the user to provide custom filenames.

The NetBSD Foundation has granted permission to remove clause 3 and 4
from their software.

Obtained from: NetBSD

Also print UNIX timestamps in getent utmpx output.

Also let getent(1) print values of ut_pid.

Allow getent(1) to display utmpx entries as well.

Because getutxent also matches the typical get*ent format of library
routines, I thought it would be a good idea to teach it how to read
utmpx databases. getent(1) just gives a raw dump, which is very useful
when debugging problems related to parsing/logging.

Build usr.bin/ with WARNS=6 by default.

Also add some missing $FreeBSD$ to keep svn happy.

cleanup code: remove superfluous comma at end of enumeration
declaration, remove useless "break" after exit(3) call, and add a
missing va_end(3) call.

Revise markup.

The port number must be network byte order.

o style: WARNS= -> WARNS?=.

Spotted by: ru

o By popular demand import getent(1) utility: a program retrieves
and displays entries from the administrative database specified by
database, using the lookup order specified in nsswitch.conf(5).

PR: bin/79903, bin/88460, bin/96536
Submitted by: Julien Gabel, Dan Nelson, Daniel J. O'Connor
Obtained from: NetBSD
Discussed with: ume, soc-bushman
MFC after: 1 month