libbb/bb_do_delay.c: shrink

function                                             old     new   delta
difftime                                               9       -      -9
bb_do_delay                                           88      38     -50
------------------------------------------------------------------------------
(add/remove: 0/1 grow/shrink: 0/1 up/down: 0/-59)             Total: -59 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/libbb/bb_do_delay.c b/libbb/bb_do_delay.c
index 3d52cc5..139dc18 100644
--- a/libbb/bb_do_delay.c
+++ b/libbb/bb_do_delay.c
@@ -13,10 +13,9 @@
 {
 	time_t start, now;
 
-	time(&start);
-	now = start;
-	while (difftime(now, start) < seconds) {
+	start = time(NULL);
+	do {
 		sleep(seconds);
-		time(&now);
-	}
+		now = time(NULL);
+	} while ((now - start) < seconds);
 }