Merge r411464 from trunk:

* info->expire and info->date are in microseconds. So convert the difference
  to seconds before comparing it to age which is in seconds.

PR: 39713
Submitted by: Owen Taylor <otaylor redhat.com>
Reviewed by: rpluem, jim, jfclere


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.2.x@720171 13f79535-47bb-0310-9956-ffa450edef68