Fix mod_expires to add Expires headers for content that isn't served

from disk (ie. the case where r->finfo.st_mode == 0), unless it is
a modification date based setting.

PR:
Obtained from:
Submitted by:	Paul Phillips <paulp@go2net.com>
Reviewed by:


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@81989 13f79535-47bb-0310-9956-ffa450edef68