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 r286964

Add ATF functional tests for fstyp(8). No ZFS or GELI tests yet.

Add ATF functional tests for fstyp(8). No ZFS or GELI tests yet.

Reviewed by: trasz, ngie
MFC after: 2 weeks
Sponsored by: SpectraLogic
Differential Revision: https://reviews.freebsd.org/D2801