test harness: allow more metadata in log files This change reworks and improves the parallel test harness to use more specialized reStructuredText fields in the log files (instead of relying on specially-placed of "magic lines" and more indirect semantical formatting); the new fields are the following: - ":recheck:": tell whether the associated test will have to be re-run by "make recheck"; - ":copy-in-global-log:": tell whether the content of the log file should be copied in the "global log" `test-suite.log'; - ":end-metadata:", which inhibits the scanning of the rest of the log file (for what concerns test metadata). Also, the special `:test-result:' value "END" has been removed, superseded by the new `:end-metadata:' field. * doc/automake.texi (Log files generation and test results recording): Document the new API and semantics. Remove or fix some obsolete comments. * lib/am/check.am ($(TEST_SUITE_LOG), recheck, recheck-html): Adjust comments and code. * lib/tap-driver (finish): Adjust, with the help of ... (must_recheck, copy_in_global_log): ... these new functions. * lib/test-driver (Main code): Adjust, with the help of ... ($recheck, $gcopy): ... these new variables. * tests/trivial-test-driver: Update to obey the new APIs. * tests/test-driver-recheck.test: Likewise. * tests/test-driver-global-log.test: Likewise. * tests/tap-passthrough.test: Relax the test, avoiding to check what is written in `test-suite.log'; such check has been moved ... * tests/tap-global-log.test: ... in this new test, and extended. * tests/test-driver-metadata-no-leading-space.test: New test. * tests/test-driver-end-test-results.test: Removed, it checked the old APIs; superseded by ... * tests/test-driver-end-metadata.test: ... this new test. * tests/tap-log.test: Improve syncing with ... * tests/test-log.test: ... this new test. * tests/parallel-tests.test: Remove some duplication w.r.t. this last new test. Updated heading comments. * tests/Makefile.am (TESTS): Update.