DrMem#1730: DR fails to detect path in Windows system install dir
DrMem#1730: DR fails to detect path in Windows system install dir

Fixes bugs in 377d5ea to properly detect the Program Files dir.

Review-URL: https://codereview.appspot.com/267110043

AmesianX/dynamorio,AmesianX/dynamorio,AmesianX/dynamorio,AmesianX/dynamorio,AmesianX/dynamorio