pjdfstest integration

Hi, I noticed that we install pjdfstest to /usr/tests/sys/pjdfstest,
but:
- it's not hooked up to the test suite, i.e.,
  "kyua test -k /usr/tests/Kyuafile" doesn't run it,
- contrib/pjdfstest doesn't seem to be updated regularly,
- the configuration is hard-coded, i.e., I can't easily run it against a
  filesystem of my choice.

How hard would it be to parameterize the tests so that we can run the
tests again a list of filesystems?  For each filesystem we'd have some
little script that sets up some scratch space, creates an empty
filesystem and points pjdfstest at it.  In some cases we'd need the test
runner to specify some additional variables, e.g., for p9fs you want the
test runner to provide a share, as we currently only support the virtio
transport.  I'm not sure if kyua can pass variables to a TAP test, so
the solution might be to wrap each pjdfstest run with an ATF test case
which handles the setup.

Is anyone interested in working on these things?