Make the repos-wc and wc helper code produce a stable child order where
possible, using the same techniques as we used to make svn status order
stable. We can't make the repository produce a stable order, but this
is at least better than random.

* subversion/libsvn_wc/diff_editor.c
  (includes): Add svn_sorts.h.
  (walk_local_nodes_diff): Sort hash instead of walking keys.
  (svn_wc__diff_local_only_dir): Obtain read info for all items at once.
    Sort hash keys and then walk them.

  (svn_wc__diff_base_only_dir,
   close_directory): Sort hash before walking.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1446374 13f79535-47bb-0310-9956-ffa450edef68