MFC r285119,r292502,r295380:

MFC r285119,r292502,r295380:

r285119 (by jmmv):

Add support for TEST_METADATA

Allow Makefiles to define generic metadata settings that apply to all test
programs defined by a Makefile.  The generic TEST_METADATA variable extends
the per-test program settings already supported via TEST_METADATA.<program>.

This feature will be useful to easily apply some settings to all programs
in a directory.  In particular, Kyua 0.12 will support parallel execution
of test programs and a bunch of them will need to be tagged as is_exclusive
to indicate that they cannot be run in parallel with anything else due to
their side-effects.  It will be reasonable to set this setting on whole
directories.

r292502:

Always expose LOCALBASE, not just when CROSS_TOOLCHAIN is defined

Instead of using which(1) to look for doxygen, look for it in <LOCALBASE>/bin .
$PATH gets mangled by make buildenv, etc so it's better to just be explicit
about the path if someone uses that for instance.

r295380:

Simplify running the FreeBSD test suite

Replace `make regress` (legacy test make target) and `make test` (incomplete
test make target added with the FreeBSD test suite) with make check as it's
consistent with other open source projects.

`make check` defaults to running tests from `.OBJDIR`, but can be overridden
with the `CHECKDIR` variable.

Add `make checkworld` target to simplify running the FreeBSD test suite from
`TESTSBASE` (i.e. the top-level tests directory), similar to buildworld.

Document `make check` and `make checkworld` in build(7).

Other minor changes:

- Rename intermediate file (`Kyuafile.auto`) to `Kyuafile` to simplify
  `make check`.
- Remove terse warnings attached to `beforetest`/`aftertest`.
- Add kyua binary check to check target in suite.test.mk; error out if it's
  not found

The MFC is [partly] contingent on other build related changes being MFCed.

X-MFC to: stable/10
Relnotes: yes

git-svn-id: svn://svn.freebsd.org/base/stable/10@313790 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f