add compile-time check to make sure only ospray::work::Work is registered
add compile-time check to make sure only ospray::work::Work is registered

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