Add an absent handler to the libsvn_wc diff processor to diff callback wrapper.

* subversion/include/private/svn_wc_private.h
  (svn_wc__diff_state_absent_t): New typedef.

* subversion/libsvn_client/repos_diff.c
  (edit_baton): Extract state handling members to their own struct.
  (send_delete_notify): Remove function. Integrate code in its only caller.
  (absent_directory,
   absent_file): Call node_absent on the diff processor instead of notifying
     directly.

  (diff_notify_baton_t): New struct.
  (diff_state_handle,
   diff_state_close): Use diff_notify_baton_t. Fold send_delete_notify code.
  (diff_state_absent): New function.

  (svn_client__get_diff_editor): Update caller.

* subversion/libsvn_wc/diff_editor.c
  (wc_diff_wrap_baton_t): Add callback.
  (wrap_node_absent): New function.
  (svn_wc__wrap_diff_callbacks): Update initialization.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1438990 13f79535-47bb-0310-9956-ffa450edef68