show_date(): fix relative dates

We pass a timestamp (i.e. number of seconds elapsed since Jan 1 1970,
00:00:00 GMT) to the function. So there is no need to "fix" the
timestamp according to the timezone.

Signed-off-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
diff --git a/date.c b/date.c
index 7acb8cb..542c004 100644
--- a/date.c
+++ b/date.c
@@ -62,12 +62,11 @@
 
 	if (relative) {
 		unsigned long diff;
-		time_t t = gm_time_t(time, tz);
 		struct timeval now;
 		gettimeofday(&now, NULL);
-		if (now.tv_sec < t)
+		if (now.tv_sec < time)
 			return "in the future";
-		diff = now.tv_sec - t;
+		diff = now.tv_sec - time;
 		if (diff < 90) {
 			snprintf(timebuf, sizeof(timebuf), "%lu seconds ago", diff);
 			return timebuf;