In the merge code: following up on r1443387, remove all now unneeded usages of
APR_HASH_KEY_STRING.

Also remove static helper function contains_path() which is now mostly a
local copy of svn_hash_gets().

* subversion/libsvn_client/merge.c
  (store_path): use svn_hash_*s().
  (contains_path): Remove function.

  (split_mergeinfo_on_revision,
   filter_self_referential_mergeinfo,
   prepare_merge_props_changed,
   record_update_delete,
   merge_file_opened,
   merge_file_added,
   merge_dir_opened,
   merge_dir_added,
   verify_touched_by_del_check,
   merge_dir_deleted,
   filter_merged_revisions,
   filter_merged_revisions,
   calculate_remaining_ranges,
   find_gaps_in_merge_source_history,
   update_wc_mergeinfo,
   record_skips_in_mergeinfo,
   remove_children_with_deleted_mergeinfo,
   pre_merge_status_cb,
   get_wc_explicit_mergeinfo_catalog,
   get_wc_explicit_mergeinfo_catalog,
   filter_natural_history_from_mergeinfo,
   do_file_merge,
   log_find_operative_subtree_revs,
   flag_subtrees_needing_mergeinfo,
   record_mergeinfo_for_dir_merge,
   record_mergeinfo_for_added_subtrees,
   log_noop_revs,
   mergeinfo_in_catalog,
   log_find_operative_revs,
   find_unmerged_mergeinfo,
   calculate_left_hand_side): Cleanup hash usage.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1443394 13f79535-47bb-0310-9956-ffa450edef68