build fix for Windows
build fix for Windows

ospray/OSPRay,MengjiaoH/ospray,MengjiaoH/ospray,MengjiaoH/ospray,MengjiaoH/ospray,ospray/OSPRay,ospray/OSPRay,wilsonCernWq/ospray,MengjiaoH/ospray,ospray/OSPRay,wilsonCernWq/ospray,wilsonCernWq/ospray