In the merge code, integrate the cmd and notify baton in preparation for
removing the merge hooking code.

No functional changes besides this baton integration step.

* subversion/libsvn_client/merge.c
  (merge_cmd_baton_t): Integrate the notification receiver baton as
    member.
  (notification_receiver_baton_t): Remove struct.
  (notification_receiver): Use merge_cmd_baton_t as baton.
  (drive_merge_report_editor): Remove argument. Update caller.
  (single_file_merge_notify): Update argument.
  (do_file_merge,
   do_mergeinfo_unaware_dir_merge,
   flag_subtrees_needing_mergeinfo,
   record_mergeinfo_for_dir_merge,
   do_mergeinfo_aware_dir_merge,
   do_directory_merge): Remove argument. Update caller.

  (do_merge): Update baton initialization.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1439002 13f79535-47bb-0310-9956-ffa450edef68