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

Migrate most of tools/regression/usr.bin/ to the new tests layout.

I'm starting with the easy cases. The leftovers need to be looked at a
bit more closely.

Note that this change _does_ modify the code of the old tests. This is
required in order to allow the code to locate the data files in the
source directory instead of the current directory, because Kyua
automatically changes the latter to a temporary directory.

Also note that at least one test is known to be broken here. Actually,
the test is not really broken: it's marked as a TODO but unfortunately
Kyua's TAP parser currently does not understand that. Will have to be
fixed separately.

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.

Reduce internal code duplication, add REGRESSION_PASSFAIL([testname]) to
handle printing of the PASS/FAIL messages. Suffix PASS/FAIL/FATAL with the
string (in $directory) where $directory is ${.CURDIR} from make(1), to
make it easier to use grep(1) and a bit of sed/awk to do statistics of
failure for some utilities over time, etc.

Add two new mostly freeform types of regression tests, and a macro for dying
ungracefully.

Comments to describe what these macros do, so that someone other than me
might be able to figure out how to write some of these tests (hint hint).

Add a simple (to be expanded) library of functions for the regression tests,
to handle the ones which output to stdout and have output in regress.$test.out,
etc. More freeform macros should and will be written, but these are the most
prominent and most straightforward sort of tests we have around, so it makes
sense to try to accomodate them.