(not so great) Fix for the hard-wired hbr regression path to work with Windows.
(not so great) Fix for the hard-wired hbr regression path to work
with Windows.

Closes #58

takahito-tejima/OpenSubdiv-exp,xldeveloper/OpenSubdiv,nyotis/OpenSubdiv,anshuarya/OpenSubdiv,takahito-tejima/OpenSubdiv-exp,lookup1980/OpenSubdiv,c64kernal/OpenSubdiv,poljere/OpenSubdiv,takahito-tejima/OpenSubdiv,anshuarya/OpenSubdiv,anshuarya/OpenSubdiv,lookup1980/OpenSubdiv,jcowles/OpenSubdiv,jcowles/OpenSubdiv,nyotis/OpenSubdiv,c64kernal/OpenSubdiv,shengfuintel/OpenSubdiv,shengfuintel/OpenSubdiv,poljere/OpenSubdiv,poljere/OpenSubdiv,nyotis/OpenSubdiv,takahito-tejima/OpenSubdiv,lookup1980/OpenSubdiv,takahito-tejima/OpenSubdiv-exp,takahito-tejima/OpenSubdiv-exp,jcowles/OpenSubdiv,c64kernal/OpenSubdiv,xldeveloper/OpenSubdiv,xldeveloper/OpenSubdiv,shengfuintel/OpenSubdiv,takahito-tejima/OpenSubdiv