cmake HAVE___ATOMIC_FETCH_ADD_4 examples

mgerhardy/caveexpress cmake/toolchains/linux-toolchain.cmake :27 

check_function_exists(__atomic_fetch_add_4 HAVE___ATOMIC_FETCH_ADD_4)

vengi-voxel/vengi cmake/system/linux.cmake :11 

check_function_exists(__atomic_fetch_add_4 HAVE___ATOMIC_FETCH_ADD_4)