Fix for PR 14556. The expiry calculations in mod_cache were
trying to perform "now + ((date - lastmod) * factor)" where
date == lastmod resulting in "now + 0". The code now follows
the else path (using the default expiration) if date is
equal to lastmod. [rx@armstrike.com (Sergey), Paul J. Reder]


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@97589 13f79535-47bb-0310-9956-ffa450edef68