clock_gettime is available from mac OS X 10.12
test_rot may be changed to check if mac os version is less than 10.12.0, ie #if defined(MACH) && __MAC_OS_X_VERSION_MIN_REQUIRED < 101200 From 10.12 clock_gettime is defined
test_rot may be changed to check if mac os version is less than 10.12.0, ie #if defined(MACH) && __MAC_OS_X_VERSION_MIN_REQUIRED < 101200 From 10.12 clock_gettime is defined