Merge branch 'jk/test-output'

Merge branch 'jk/test-output'

When TEST_OUTPUT_DIRECTORY setting is used, it was handled somewhat
inconsistently between the test framework and t/Makefile, and logic
to summarize the results looked at a wrong place.

* jk/test-output:
  t/Makefile: don't define TEST_RESULTS_DIRECTORY recursively
  test output: respect $TEST_OUTPUT_DIRECTORY
  t/Makefile: fix result handling with TEST_OUTPUT_DIRECTORY