Merge branch 'ad-parallel-tests' into next

Merge branch 'ad-parallel-tests' into next

* ad-parallel-tests:
  parallel-tests: New target recheck-html.
  parallel-tests: redo lazy checking: recheck and RECHECK_LOGS.
  parallel-tests: do not mark check-TESTS as `.MAKE'.
  parallel-tests: warn about $(srcdir), $(top_srcdir) in TESTS.
  check-html: Always create HTML output, note conversion failure.
  parallel-tests: per-extension test driver: <EXT>_LOG_COMPILER.
  parallel-tests: also record logs of SKIPped tests.
  Minor optimization in parallel-tests text box creation.