Fixing the star on unit tests for Windows consoles

Summary: On Windows consoles, the star on the unit tests (I'm assuming it's a Unicode character of some kind), doesn't render correctly and you just get garbage.  This fixes it so that on Windows, it falls back to just using an ASCII asterisk.

Test Plan: On Windows run some unit tests, the star should now be a plain asterisk.

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D6087