Fix check count if CHECK_EQUAL evaluates to 'true'

CHECK_EQUAL() does not increment the check count if it evaluates to true because the
effective check function is called in the fail case only (to avoid multiple evaluations of expected/actual).
The (quick) solution is to call an arbitrary passing check if CHECK_EQUAL passes.

By the way: this would be a great place to have a template function. While I fully support the
decision against using STL, 'plain' templates should be OK for post-2005 embedded C++ compiler.