Make the repository wc-diff functions svn_wc__diff_local_only_file() and
svn_wc__diff_local_only_dir() library-wide available in preparation for
fixing the notice-ancestry support in the wc-only-diff.

No functional changes.

* subversion/libsvn_wc/diff.h
  (New file).
  (svn_wc__diff_local_only_file,
   svn_wc__diff_local_only_dir): New prototypes.

* subversion/libsvn_wc/diff_editor.c
  (includes): Add diff.h.
  (report_local_only_file,
   report_local_only_dir): Remove prototypes.

  (walk_local_nodes_diff): Update caller.

  (report_local_only_file): Transform this function into...
  (svn_wc__diff_local_only_file): ... this by replacing edit baton usages with
    arguments.

  (report_local_only_dir): Transform this function into...
  (svn_wc__diff_local_only_dir): ... this by replacing edit baton usages with
    arguments.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1446250 13f79535-47bb-0310-9956-ffa450edef68