Fix work command not to spend more mobility than requested

Culprit is careless rounding in work().

src/lib/commands/work.c

@@ -79,7 +79,7 @@ work(void)
 	    continue;
 	}
 	eff_amt = MIN(land.lnd_mobil, work_amt);
-	w = ldround(((double)eff_amt * land.lnd_effic / 600.0), 1);
+	w = (eff_amt * land.lnd_effic) / 600;
 	if (w < 1) {
 	    pr("%s doesn't work enough to change efficiency (try increasing amount)\n",
 	       prland(&land));