Add 'local' authz provider that matches connections originating

on the local host.  PR 19938.

Also remove some cruft from mod_authz_host (we don't need a per-dir config)


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1001207 13f79535-47bb-0310-9956-ffa450edef68