recheck: behave better with non-GNU make

recheck: behave better with non-GNU make

* automake.in (handle_tests): Also substitute '%CHECK_DEPS%' with
the value of the '@check' array, containing the list of early
test dependencies like '$(check_SCRIPTS)', $(check_PROGRAMS)',
etc.
* lib/am/check.am (recheck): Explicitly depend on '%CHECK_DEPS%'.
(check, recheck): Unify the implementation of their recipes, with
different code paths taken depending on the name of the target.
This makes the implementation of "recheck" less brittle in the
process (especially when non-GNU make and AM_MAKEFLAGS overriding
are involved).
* lib/am/check-html.am (check-html, recheck-html): Likewise.
* tests/check.test: Adjust to avoid spurious failure.
* tests/parallel-tests2.test: Improve coverage.