check_cxx_source_compiles("
#include <time.h>
#include <unistd.h>

int main(int, char **) {
    struct timespec ts;
    clock_gettime(CLOCK_REALTIME, &ts);
    return 0;
}
" HAVE_GETTIME)

check_library_exists(c clock_gettime "" HAVE_GETTIME)

check_library_exists(rt clock_gettime "" HAVE_GETTIME)