if there are any ExpiresByType directives for the current

scope, defer the setting of the expiration header fields
to an output filter, which can then apply any ExpiresByType
or ExpiresDefault settings -- including to dynamic documents.
Backport Coar's patch to Apache 2.1


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/APACHE_2_0_BRANCH@99907 13f79535-47bb-0310-9956-ffa450edef68