tests: depend on the programs we're testing

tests: depend on the programs we're testing

* tests/local.mk ($(TEST_LOGS)): Depend on $(PROGRAMS), so that
tests are rerun when any program is rebuilt.  Technically, we could
specify precisely which few programs are dependents of each test,
but that can come later, if deemed worth the trouble and maintenance
burden.  Also, there is the issue of the primary program(s) being
tested (i.e., those itemized via print_ver_) versus those that are
tested incidentally: for example, nearly every test exercises "rm"
when its clean-up code removes files.