Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

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

Reassign copyright statements on several files from Advanced
Computing Technologies LLC to Hudson River Trading LLC.

Approved by: Hudson River Trading LLC (who owns ACT LLC)
MFC after: 1 week

Migrate tools/regression/{usr.bin/lastcomm,usr.sbin}/ to the new tests layout.

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.

Change etcupdate tests to return 1 on test failures.

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

- Refresh /etc/localtime after each update using tzsetup -r.
- Regenerate /var/db/services.db when /etc/services changes.

MFC after: 1 week

Add a pre-world mode of updating similar to the -p option that can be
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