Following up on r1440315, stop using the state output arguments as local
variables to store merge results.

* subversion/libsvn_client/merge.c
  (merge_file_changed): Use local variables to keep merge state.
  (merge_file_added): Remove unneeded assignment.
  (merge_dir_props_changed): Use local variable to keep merge state.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1440325 13f79535-47bb-0310-9956-ffa450edef68