Separate the two meanings of 'ignore ancestry' in merge functions. One
meaning is ignore mergeinfo; the other is diff unrelated nodes as if they
are related. Extend this separation almost up to the public API, for now.

* subversion/libsvn_client/merge.c
  (merge_cmd_baton_t): Instead of 'ignore_ancestry' have two separate flags
    'ignore_mergeinfo' and 'diff_ignore_ancestry'.
  (HONOR_MERGEINFO): Update the reference: use 'ignore_mergeinfo'.
  (drive_merge_report_editor, do_file_merge): Update the references: use
    'diff_ignore_ancestry'.
  (do_merge, merge_locked, merge_peg_locked): Instead of 'ignore_ancestry'
    take two separate flags.
  (merge_cousins_and_supplement_mergeinfo): Instead of 'ignore_ancestry'
    take just a 'diff_ignore_ancestry' flag, since this function is only
    used with mergeinfo.
  (merge_reintegrate_locked, do_automatic_merge_locked): Take a new
    'diff_ignore_ancestry' flag, which was previously assumed to be false.
  (svn_client_merge4,
   svn_client_merge_peg4): Pass the API's 'ignore_ancestry' flag for both.
  (svn_client_merge_reintegrate,
   svn_client_do_automatic_merge): Pass FALSE for both, as we don't want to
    ignore mergeinfo and don't have an API flag for ignoring diff ancestry.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1436990 13f79535-47bb-0310-9956-ffa450edef68