fix mac build.
fix mac build.

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