Function increment_overflow_time

localtime.c:2526–2544

	time_t				t;
	struct tm			yourtm, mytm;

	*okayp = false;
	mktmcpy(&yourtm, tmp);

	min = yourtm.tm_min;
	if (do_norm_secs) {
	  min += yourtm.tm_sec / SECSPERMIN;
	  yourtm.tm_sec %= SECSPERMIN;
	  if (yourtm.tm_sec < 0) {
	    yourtm.tm_sec += SECSPERMIN;
	    min--;
	  }
	}

	hour = yourtm.tm_hour;
	hour += min / MINSPERHOUR;
	yourtm.tm_min = min % MINSPERHOUR;
	if (yourtm.tm_min < 0) {
	  yourtm.tm_min += MINSPERHOUR;
	  hour--;
	}