This change was originally going to only migrate the usr.sbin tests but, as
it turns out, the usr.sbin/sa/ tests require files from usr.bin/lastcomm/
so it's better to just also migrate the latter at the same time.  The other
usr.bin tests will be moved separately.

To make these tests work within the test suite, some of them have required
changes to prevent modifying the source directory and instead just rely on
the current directory for file manipulation.

This is a prerequisite for hooking these tests into the test suite.  And,
fortunately, all tests seem to pass!

- Regenerate /var/db/services.db when /etc/services changes.

MFC after:	1 week

- Fix ALWAYS_INSTALL to take precedence over the FreeBSD ID checks.
  In particular, always install a file where the only change was
  the FreeBSD ID even if -F is specified.
- Fix the -F option in the case that the only upstream change is a
  change in the FreeBSD ID and the local file is removed.
- Add tests for these two cases.

passed to mergemaster.  In this mode, only changes to /etc/master.passwd
and /etc/group are merged to /etc.  In addition, it uses a temporary
tree to stage these changes rather than overwriting the existing
'current' and 'previous' trees so that a full update can be run after
a normal installworld has completed.

MFC after:	2 weeks

to test.  This allows a non-installed version of the script to be tested
more easily.

not updated as part of `make installworld' such as files in /etc.  It
manages updates by doing a three-way merge of changes made to these files
against the local versions.  It is also designed to minimize the amount
of user intervention with the goal of simplifying upgrades for clusters
of machines.

The primary difference from mergemaster is that etcupdate requires less
manual work.  The primary difference from etcmerge is that etcupdate
updates files in-place similar to mergemaster rather than building a
separate /etc tree.

Requested by:	obrien, kib, theraven, joeld (among others)