Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

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

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Set magic fbsd:nokeywords property that allows files to bypass
keyword expansion. (file-specific replacement for CVSROOT/exclude)

Switch over to a different, more flexible test output protocol that's
understood by Perl's Test::Harness module and prove(1) commands.

Update README to describe the new protocol. The work's broken down into
two main sets of changes.

First, update the existing test programs (shell scripts and C programs)
to produce output in the ok/not ok format, and to, where possible, also
produce a header describing the number of tests that are expected to be
run.

Second, provide the .t files that actually run the tests. In some cases
these are copies of, or very similar too, scripts that already existed.
I've kept the old scripts around so that it's possible to verify that
behaviour under this new system (in terms of whether or not a test fails)
is identical to the behaviour under the old system.

Add a TODO file.

Move all remaining tests except for:
make(1): Does not work like the other tests. Its Makefile is
self-testing.
m4(1): It uses complex voodo to test GNU m4(1) features.

To the new framework. I had worried about passing the binary data that
uudecode(1)'s test passes to diff(1) might give a user something nasty,
but this is unlikely to happen as even with an unmodified old nasty
diff(1) which doesn't recognise many binary files, these binary files
are recognised. Using $DIFF instead of `diff' in the library and making
it possible to override this with `cmp -s' might be nice some day, but
as of this second, there's no immediate need.

Prefix tests with PASS and FAIL, to make grepping easier, and note this in
the README.

This affects only the base-system regression tests, of course.

A simple test for join(1) based on tjr's test case for -o 0.

Partially based on: PR standards/36072