Remove an unneeded wrapping layer in svnrdumps dump logic.

* subversion/svnrdump/dump_editor.c
  (handler_baton): Remove struct.
  (window_handler): Remove function.
  (apply_textdelta): Just pass the values from svn_txdelta_to_svndiff3 as
    handler instead of a wrapper that doesn't do anything.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1557730 13f79535-47bb-0310-9956-ffa450edef68