Replace the use of svn_fs_node_id + svn_fs_compare_ids with
simple calls to svn_fs_node_relation.

* subversion/libsvn_fs/editor.c
  (can_modify): Simplify using the new API.

* subversion/libsvn_repos/delta.c
  (svn_repos_dir_delta2): Ditto.

* subversion/mod_dav_svn/util.c
  (dav_svn__get_safe_cr): Ditto.

* subversion/mod_dav_svn/version.c
  (dav_svn__checkout): Ditto.

* subversion/libsvn_repos/rev_hunt.c
  (svn_repos_trace_node_locations): Ditto.
  (svn_repos_deleted_rev): Same, plus use svn_fs_check_path to test
                           for path validity instead of checking the
                           result of svn_fs_node_id.

git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1554807 13f79535-47bb-0310-9956-ffa450edef68