Allow UNITTEST_STOP to return the error code, use the fail & abort
macros to indicate test failure and return success instead of fail if
the unit test can't test anything because of missing features at
compile-time. A couple of tests could never fail because they were
overriding the failure return code.
- they are mostly pointless in all major jurisdictions
- many big corporations and projects already don't use them
- saves us from pointless churn
- git keeps history for us
- the year range is kept in COPYING
checksrc is updated to allow non-year using copyright statements
Closes#10205
