Turning TESTS on by default

[Julio Merino]

On Fri, Jun 6, 2014 at 11:33 PM, Konstantin Belousov
<kostikbel at gmail.com> wrote:
> It is the same as the debugging kernel. The INVARIANTS, WITNESS, DEBUG
> and DIAGNOSTIC options are not enabled for the user consumption.

No; this is not the same at all. All the options you mention introduce
a performance penalty on the system at *run* time and the _only_ way
to get rid of such penalty completely is to disable the options at
*build* time (sysctl doesn't make the cut because the system would
still need to check a boolean value). Because these toggles affect
run-time performance, and because they are intended for developers
only, they are not the default on release builds.

Building the test suite has no impact whatsoever on the system at
run-time. The test suite is just a bunch of files in a self-contained
location. We ought to ship such files as tests.tgz to give users a
very easy way of not installing them though.