check_c_source_compiles("
  #include <mach/clock.h>
  #include <mach/mach.h>
  int main() {
      clock_serv_t cclock;
      mach_timespec_t mts;
      host_get_clock_service(mach_host_self(), CALENDAR_CLOCK, &cclock);
      clock_get_time(cclock, &mts);
      return mach_port_deallocate(mach_task_self(), cclock);
  }" CMT_HAVE_CLOCK_GET_TIME)