BUG/MINOR: calltrace: fix 'now' being used in place of 'date'

Since commit 28360dc ("MEDIUM: clock: force internal time to wrap early
after boot") we have a much clearer distinction between 'now' (the internal,
drifting clock) and 'date' (the wall clock time). The calltrace code was
using "now" instead of "date" since the value is displayed to humans.

No backport is needed.

src/calltrace.c

@@ -76,7 +76,7 @@ static int open_trace()
 	if (!log)
 		log = stderr;
 
-	now_ptr = &now;
+	now_ptr = &date;
 	if (getenv("HAPROXY_TRACE_FAST") != NULL) {
 		fast_time = 1;
 		now_ptr = &trace_now;