grdc(6): fix timekeeping for user-supplied value n

- Keep timespec 'now' and 'delay' separate to avoid confusion
- Increase user-supplied n to run _at least_ n seconds, not max n

PR:            bin/149130 (based on)
Submitted by:  Andy Farkas
MFC after:     2 weeks

games/grdc/grdc.c

@@ -29,7 +29,7 @@
 #define YDEPTH  7
 
 /* it won't be */
-time_t now; /* yeah! */
+struct timespec now; /* yeah! */
 struct tm *tm;
 
 short disp[11] = {
@@ -57,7 +57,7 @@ sighndl(int signo)
 int
 main(int argc, char *argv[])
 {
-	struct timespec ts;
+	struct timespec delay;
 	long t, a;
 	int i, j, s, k;
 	int n;
@@ -89,7 +89,7 @@ main(int argc, char *argv[])
 	}
 
 	if (argc > 0)
-		n = atoi(*argv);
+		n = atoi(*argv) + 1;
 	else
 		n = 0;
 
@@ -135,10 +135,10 @@ main(int argc, char *argv[])
 
 		attrset(COLOR_PAIR(2));
 	}
-	time(&now);
+	clock_gettime(CLOCK_REALTIME_FAST, &now);
 	do {
 		mask = 0;
-		tm = localtime(&now);
+		tm = localtime(&now.tv_sec);
 		set(tm->tm_sec%10, 0);
 		set(tm->tm_sec/10, 4);
 		set(tm->tm_min%10, 10);
@@ -192,19 +192,16 @@ main(int argc, char *argv[])
 		}
 		movto(6, 0);
 		refresh();
-		clock_gettime(CLOCK_REALTIME_FAST, &ts);
-		if (ts.tv_sec == now) {
-			if (ts.tv_nsec > 0) {
-				ts.tv_sec = 0;
-				ts.tv_nsec = 1000000000 - ts.tv_nsec;
-			} else {
-				ts.tv_sec = 1;
-				ts.tv_nsec = 0;
-			}
-			nanosleep(&ts, NULL);
-			now = ts.tv_sec + 1;
-		} else
-			now = ts.tv_sec;
+		clock_gettime(CLOCK_REALTIME_FAST, &now);
+		if (delay.tv_nsec > 0) {
+		    delay.tv_sec = 0;
+		    delay.tv_nsec = 1000000000 - now.tv_nsec;
+		} else {
+		    delay.tv_sec = 1;
+		    delay.tv_nsec = 0;
+		}
+		nanosleep(&delay, NULL);
+		now.tv_sec++;
 		if (sigtermed) {
 			standend();
 			clear();