Merge branch 'jk/unit-tests-buildfix' into js/unit-test-suite-runner

* jk/unit-tests-buildfix: t/Makefile: say the default target upfront t/Makefile: get UNIT_TESTS list from C sources Makefile: remove UNIT_TEST_BIN directory with "make clean" Makefile: use mkdir_p_parent_template for UNIT_TEST_BIN