MFC r289172,r290254:

r289172:

Refactor the test/ Makefiles after recent changes to bsd.test.mk (r289158) and
netbsd-tests.test.mk (r289151)

- Eliminate explicit OBJTOP/SRCTOP setting
- Convert all ad hoc NetBSD test integration over to netbsd-tests.test.mk
- Remove unnecessary TESTSDIR setting
- Use SRCTOP where possible for clarity

r290254:

Remove unused variable (SRCDIR)

MFC various moves of tools/regressions/ tests to the new infrastructure.

- r263220 Migrate tools/regression/sbin/ to the new tests layout.
- r263222 Add Makefile missed in r263220.
- r263226 Migrate tools/regression/{usr.bin/lastcomm,usr.sbin}/ to the new tests layout.
- r263227 Migrate most of tools/regression/usr.bin/ to the new tests layout.
- r263345 Expand tabs that sneaked in into spaces.
- r263346 Migrate tools/regression/usr.bin/make/ to the new tests layout.
- r263348 Add Makefiles missed in r263346.
- r263351 Migrate tools/regression/usr.bin/pkill/ to the new tests layout.
- r263388 Mark multi_test as requiring /usr/share/dict/words.
- r263814 Fix path to the run.pl script to let these tests run.
- r264742 Prevent building tests when bootstrapping make.

This is 'make tinderbox' clean.

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.