set(CMAKE_SYSTEM_NAME Dumdidum)
set(CMAKE_SYSTEM_VERSION "1.0")

set(CMAKE_C_COMPILER /opt/foo/bin/arm-elf-gcc)
set(CMAKE_C_OUTPUT_EXTENSION ".foo")

set(CMAKE_CXX_COMPILER /opt/bar/bin/cl.exe)
set(CMAKE_CXX_OUTPUT_EXTENSION ".bar")