one more round of walker cleanup: remove some items that are internal to the

    FS provider from the public API; bang up the FS internals for the
    now-private items and mechanisms; a bit more revamp to the FS walker
    top-level APIs to narrow in on obsoleting dav_walker_ctx.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@86886 13f79535-47bb-0310-9956-ffa450edef68