fixing a int->float warning for MSVC
fixing a int->float warning for MSVC

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