Rather than continuing to canonicalize within directory_walk (very time

  Rather than continuing to canonicalize within directory_walk (very time
  consuming on all but *nix systems) we temporarily canonicalize to compare
  the results of the many merges, and fail on a mismatch.

  The apr_filepath_merge and ap_server_root_relative calls now merge the
  file _by canonicalizing it_.  That includes resolving all /../, /./,
  and // misnomers.

  A minor effort is required to figure out who all munges the r->filename
  in an inappropriate manner.

  The final (return to optimized state) probably involves setting an
  r->goodname argument to r->filename, every time we properly merge
  through ap_server_root_relative or apr_filepath_merge().

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@90573 13f79535-47bb-0310-9956-ffa450edef68