ptunit: a new unit test system

Check doesn't support windows and we don't really need all its features.

Add a very simple framework for our unit tests.

Change-Id: I5b7a79977f61169504d28dd1dc816c050d1c10ad
Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>
ptunit: last-ip

Move last-ip unit tests from check to ptunit.

Change-Id: I1bf009b100461f0dab5da1e82a6a486717d6099a
Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>
ptunit: tnt-cache

Move tnt-cache unit tests from check to ptunit.

Change-Id: Id228961612b71585fafa6234dfa5cd84832adad2
Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>
ptunit: query

Move query unit tests from check to ptunit.

Change-Id: I208c0af9559bf2e9877af3d0e1cbf295120fab8a
Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>