- Copy stable/10 (r259064) to releng/10.0 as part of the
10.0-RELEASE cycle.
- Update __FreeBSD_version [1]
- Set branch name to -RC1

[1] 10.0-CURRENT __FreeBSD_version value ended at '55', so
start releng/10.0 at '100' so the branch is started with
a value ending in zero.

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

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

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

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.