fs-tests: integck: implement own version of CHECK

fs-tests: integck: implement own version of CHECK

Remove the final dependency on the common code - the CHECK() macro.
Now we are finally independent. The reason we needed this is that
we are going to improve integck to handle errors more gracefully,
in order to support failure testing better. And this requires changes
in the common code, but it is ancient and shared by many tests, and
we do not want to touch it. So we better make integck independent
and concentrate on integck only.

This patch also removes Makefile dependencies. And while on it, remove
the broken 'tests' target.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>