potential fix for MSVC12
potential fix for MSVC12

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