more gitlab build job tweaks for centos6
more gitlab build job tweaks for centos6

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