fix Issue 9330 - Cannot run dmd test suite with MSYS

This is a workaroud for the MSYS bug:
http://sourceforge.net/tracker/?func=detail&atid=102435&aid=1100932&group_id=2435
Merge pull request #1500 from 9rnsr/fix9330

Issue 9330 - Cannot run dmd test suite with MSYS