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 r267265: truncate: Detect integer overflow, fix relative sizes, add tests.

The change to expand_number (r204654) broke detection of too large sizes and
relative sizes ('+'/'-').

Also add some tests.

The usr.bin/truncate/Makefile is slightly different in the MFC because
src.opts.mk does not exist in stable/10.

PR: 190735
Submitted by: Kirk Russell

truncate: Detect integer overflow, fix relative sizes, add tests.

The change to expand_number (r204654) broke detection of too large sizes and
relative sizes ('+'/'-').

Also add some tests.

PR: 190735
Submitted by: Kirk Russell
MFC after: 1 week