make unittest failure foo a script

- first of all, code from CppunitTest.mk used from PythonTest.mk is bad
  anyway
- also, this shortens and removes noise from the commandline executed

Change-Id: I6c5b41a0c497b766c3293aeec5c59240aa3ef37c
smoketest cant work without extensions

Change-Id: I58af85205cce89c2eff3db24a477171ce39d47dc