check: small cleanups and refactorings in test harness and drivers * lib/tap-driver (yn): New subroutine, converts a boolean value to a "yes" or "no" string. (write_test_results): Use it, and related reformatting. * lib/test-driver (trap): Also remove the `.trs' file on signals, for extra safety. (fatal): Remove this function, it's never used. ($logfile, $trsfile): Renamed ... ($log_file, $trs_file): ... to these, for clarity, and in order to be more consistent with the `tap-driver' script. Improve a couple of comments. * automake.in (handle_tests): Don't define anymore the now-obsolete make macro `$(TEST_LOGS_TMP)', nor add it to the list of files to be removed upon "make mostlyclean". * lib/am/check.am ($(TEST_SUITE_LOG)): New shell function `f_ok', tells whether a path refers to an existing, regular, readable file. Use it throughout. (recheck): Be safer w.r.t. make implementation that run recipes with `errexit' shell flag active.