Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

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

Merge r267482,r267483,r267486,r267577,r267671,r267672 from head:

Remove send-pr and fix up all references to it. Replace it with a
stub send-pr directing people towards the web site.

MFC several WITH_TESTS-related documentation fixes.

- r258014 Document WITH_TESTS src.conf(5) option.
- r263089 Fix description of WITHOUT_BMAKE's purpose.
- r264408 Fix test suite name in src.conf(5).
- r264410 Document how to install the test suite.
- r264412 Add FreeBSD 10.1 to the list of recognized releases for Fx.
- r264413 Miscellaneous fixes to tests(7).

MFC r263428

share/man/man7/tests.7
Added a section on test suite configuration, and cleaned up up grammar
errors and awkward prose. The config variables were discussed on
freebsd-testing.

Set up the /usr/tests hierarchy.

This is a MFC of the following into stable/10:
- r257097 Set up the /usr/tests hierarchy.
- r257098 Add missing WITHOUTTESTS file.
- r257100 Add a tests(7) manual page.
- r257105 Disable WITHTESTS= for now.
- r257848 Fix buildworld when WITHTESTS is enabled.
- r257850 Subsume the functionality of MKATF into MKTESTS.
- r257851 Handle the removal of the test suite when WITHOUTTESTS=yes.
- r257852 Install category Kyuafiles from their category directories.
- r258232 Install BSD.tests.mtree when MKTESTS is yes.

Note that building with WITH_TESTS is still broken at this point (and
hence why WITHOUT_TESTS is the set as the default). Subsequent pullups
will fix the remaining issues.

Add a tests(7) manual page.

This manual page intends to describe the structure and behavior of
the FreeBSD test suite installed in /usr/tests. The contents have
been inherited from the NetBSD manual page.

As a side effect, this also updates the hier(7) manual page to
mention /usr/tests and points at tests(7) for more details.

Submitted by: Julio Merino jmmv google.com
Reviewed by: sjg
MFC after: 2 weeks