test: report summary even when aborting

test: report summary even when aborting

In certain cases of test suite failure, the summary report was not
being printed.  In particular, any failure on the parallel test suite,
and any aborted test in the serialized test suite would end up hiding
the summary.

It's better to always show the summary where we can (while preserving
the return code).  If we do abort due to this high-level failure,
though, we should also announce to the user that we're doing so as
close to the end of the process as possible, to make it easier to find
the problem.

Signed-off-by: Daniel Kahn Gillmor <dkg@fifthhorseman.net>