Fix a year 2100+ formatting problem with mod_usertrack.

PR:		1342
Submitted by:	Paul Eggert <eggert@twinsun.com>
Reviewed by:	Dean Gaudet, Marc Slemko, Martin Kraemer


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@79511 13f79535-47bb-0310-9956-ffa450edef68