Add LINUX_PPC for Bluegene detection
Add LINUX_PPC for Bluegene detection

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