Expose this as part of the API. That way, other code/modules

which want to overload mod_proxy's trans phase can use it to
handle ProxyPass as well, without requiring monkeying
with conf->aliases...

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1068400 13f79535-47bb-0310-9956-ffa450edef68