0: Don't activate any unit-test modules.
This is the default for normal code compilation and does not make much sense
for actual unit testing.
1: Activate all unit-unit test modules.
rhd_baseradUT_module: Activate this module.
rhd_meanUT_module: Activate this module.
rhd_recUT_module: Activate this module.
rhd_baseradUT_module rhd_meanUT_module: Activate these two modules
(this is an example; any combination is possible).