Turning TESTS on by default

Hello all,


TL;DR
-----

I plan to turn the TESTS src.conf knob ON by default on Tuesday once I
have been able to perform enough sanity-checks of the build and all of
them pass.

The impact of this is that the FreeBSD Test Suite (see tests(7)) will
be built and installed by default under /usr/tests/ along with the
private atf libraries and binaries. There should be no other changes
and this should be transparent to everyone.

If this happens to break the world in any way, we can trivially roll
the change back to fix the fallout.


Some details
------------

TESTS was never intended to be disabled by default. However, the
original patches that were committed months ago related to this
feature broke the build and the easiest way out (instead of reverting
the commits) was to set the knob to disabled. Unfortunately, it stayed
that way even after the discovered problems were fixed.

I am confident enough now that we have ironed out all major issues
that this might introduce, so it is about time to enable TESTS by
default again in HEAD.

The benefits of this are that 1) we allow end users (especially
consumers of binary releases!) to run the tests out of the box, as it
has always been intended; and 2) we will be able to run the official
release builds through testing via Jenkins, instead of having to issue
custom builds.

Actual change: https://phabric.freebsd.org/D188


I will update this thread when the change is committed and/or with any updates.

Please let me know if I'm missing anything.

Cheers