testsuite: optimize tests on TAP for speed and against duplication

testsuite: optimize tests on TAP for speed and against duplication

The creation and configuration of common files and data used by
many tests on TAP is, with this change, factored out into a new
dedicated auxiliary test, from which those tests will depend upon.
This reduces code duplication in tests and, more importantly,
offers a noticeable speedup in the involved tests (30-40%).

* tests/tap-common-setup.test: New test, setting up the common
files and data used by various tests on TAP support.
* tests/tap-setup.sh: New file, to be sourced by tests wanting to
bring in data generated by `tap-common-setup.test'.
* tests/tap-autonumber.test: Update to use the pre-computed data
files.
* tests/tap-bailout.test: Likewise.
* tests/tap-color.test: Likewise.
* tests/tap-deps.test: Likewise.
* tests/tap-diagnostic.test: Likewise.
* tests/tap-empty-diagnostic.test: Likewise.
* tests/tap-empty.test: Likewise.
* tests/tap-escape-directive.test: Likewise.
* tests/tap-exit.test: Likewise.
* tests/tap-signal.test: Likewise.
* tests/tap-fancy.test: Likewise.
* tests/tap-fancy2.test: Likewise.
* tests/tap-global-log.test: Likewise.
* tests/tap-global-result.test: Likewise.
* tests/tap-html.test: Likewise.
* tests/tap-log.test: Likewise.
* tests/tap-merge-stdout-stderr.test: Likewise.
* tests/tap-no-merge-stdout-stderr.test: Likewise.
* tests/tap-message-0.test: Likewise.
* tests/tap-no-disable-hard-error.test: Likewise.
* tests/tap-no-spurious-summary.test: Likewise.
* tests/tap-no-spurious.test: Likewise.
* tests/tap-not-ok-skip.test: Likewise.
* tests/tap-numeric-description.test: Likewise.
* tests/tap-out-of-order.test: Likewise.
* tests/tap-passthrough.test: Likewise.
* tests/tap-passthrough-exit.test: Likewise.
* tests/tap-plan.test: Likewise.
* tests/tap-plan-corner.test: Likewise.
* tests/tap-plan-corner2.test: Likewise.
* tests/tap-plan-errors.test: Likewise.
* tests/tap-realtime.test: Likewise.
* tests/tap-recheck-logs.test: Likewise.
* tests/tap-skip-whole.test: Likewise.
* tests/tap-todo-skip-together.test: Likewise.
* tests/tap-todo-skip-whitespace.test: Likewise.
* tests/tap-todo-skip.test: Likewise.
* tests/tap-unplanned.test: Likewise.
* tests/tap-with-and-without-number.test: Likewise.
* tests/tap-xfail-tests.test: Likewise.
* tests/tap-skip-whole-whitespace.test: Likewise, and remove
redundant definitions of `$sp' and `$tab' (they are already
defined in `tests/defs').
* tests/tap-whitespace-normalization.test: Likewise.
* tests/Makefile.am (TESTS): Update.
(EXTRA_DIST): Distribute `tap-setup.sh'.
(tap_with_common_setup_tests, tap_with_common_setup_logs)): New
variables, holding respectively the list of tests using the files
pre-computed by `tap-common-setup.test', and the list of their
corresponding log files.
(tap_other_tests): New variable, holding the list of other tests
on TAP support.
($(tap_with_common_setup_logs)): Depend on `tap-common-setup.log'
and `tap-setup.sh'.