Add the new directory_walk logic, eliminating get_path_info and
  check_symlinks, in a protected define REPLACE_PATH_INFO_METHOD.

  This allows others to work on vetting, caching, etc, while keeping
  the existing logic stable till it's sufficiently optimal for beta.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@89847 13f79535-47bb-0310-9956-ffa450edef68