Merge branch 'sk/reftable-clarify-tests'

The reftable unit tests are now ported to the "clar" unit testing framework. * sk/reftable-clarify-tests: t/unit-tests: finalize migration of reftable-related tests t/unit-tests: convert reftable stack test to use clar t/unit-tests: convert reftable record test to use clar t/unit-tests: convert reftable readwrite test to use clar t/unit-tests: convert reftable table test to use clar t/unit-tests: convert reftable pq test to use clar t/unit-tests: convert reftable merged test to use clar t/unit-tests: convert reftable block test to use clar t/unit-tests: convert reftable basics test to use clar test framework t/unit-tests: implement clar specific reftable test helper functions