When some of the individual tests fail to run, the `make test` target would
still pass since test/problems would not return an error which could hide the
fact that there are problems in the test.
With this change, if you do not have the python dateutil package, you will now
get output like:
'test_totals.t' failed to run any tests.
Passed: 975
Failed: 1
Unexpected successes: 0
Skipped: 0
Expected failures: 0
Runtime: 4.83 seconds
Or, if you do not have UTF-8 encoding set in your language you will get
something like:
'track.t' failed to run all tests.
'stop.t' failed to run all tests.
'start.t' failed to run all tests.
'test_totals.t' failed to run all tests.
Passed: 941
Failed: 50
Unexpected successes: 0
Skipped: 0
Expected failures: 0
Runtime: 4.55 seconds
