Fix litmus test copy_nodestcoll; 2518 requires that MKCOL MUST fail

with 409 on missing intermediates:

* modules/dav/fs/repos.c (dav_fs_create_collection): Give a 409 rather
than a 403 if apr_dir_make fails with ENOENT.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@102946 13f79535-47bb-0310-9956-ffa450edef68