syslog-format: don't try to turn a timestamp to unixtime if one is no…

…t present

If the timestamp is not actually there in the message, we still tried
to call convert_and_normalize_wall_clock_time_to_unix_time_with_tz_hint(),
which in turn calls mktime(), which is a heavyweight operation.

Let's not do that.

Signed-off-by: Balazs Scheidler <balazs.scheidler@axoflow.com>

modules/syslogformat/syslog-format.c

@@ -270,7 +270,7 @@ _syslog_format_parse_timestamp(LogMessage *msg, UnixTime *stamp,
       result = scan_rfc5424_timestamp(data, length, &wct);
     }
 
-  if ((parse_flags & LP_NO_PARSE_DATE) == 0)
+  if (result && (parse_flags & LP_NO_PARSE_DATE) == 0)
     {
       convert_and_normalize_wall_clock_time_to_unix_time_with_tz_hint(&wct, stamp, recv_timezone_ofs);