While trying to get the unit tests working again I stumbled over all those
things that I thought could be better^TM.
Now we also know "TODO: why does this make the test fail?" - because
the unit tests are brittle AF ... and we have to init the subsystems
we use in the test, otherwise the cleanup will fail...
BTW. you can now also only run a single test ... or a pattern or so ...
you'd have to read how `cmocka_set_test_filter()` works exactly.
Signed-off-by: Steffen Jaeckel <s@jaeckel.eu>