Minor system.cmake tweak
Minor system.cmake tweak

biddisco/CMake,shuaibarshad/KAUST-CMake,shurikasa/CMake,hernando/vmmlib,shuaibarshad/KAUST-CMake,biddisco/CMake,rballester/vmmlib,rballester/vmmlib,shurikasa/CMake,biddisco/CMake,ptoharia/CMake,tribal-tec/vmmlib,biddisco/CMake,shurikasa/CMake,BlueBrain/Tuvok,jafyvilla/CMake,ptoharia/CMake,BlueBrain/Tuvok,shuaibarshad/KAUST-CMake,rballester/vmmlib,jafyvilla/CMake,jafyvilla/CMake,hernando/vmmlib,ptoharia/CMake,BlueBrain/Tuvok,ptoharia/CMake,shuaibarshad/KAUST-CMake,shurikasa/CMake,jafyvilla/CMake,hernando/vmmlib