Remove the difference in handling single-file and directory merges in the
merge notification processing.

* subversion/libsvn_client/merge.c
  (merge_cmd_baton_t): Remove separate variables and add struct specifically
    for this task.
  (notify_merge_begin): Handle single file merges as ordinary merges.
  (do_file_merge): Create a fake children_with_mergeinfo array and keep it
    up to date.

  (do_mergeinfo_aware_dir_merge,
   do_directory_merge,
   do_merge): Simplify drive reset code.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1442598 13f79535-47bb-0310-9956-ffa450edef68