On the fsx-id branch:
Replace the svn_fs_id_t in change_t with our FSX internal ID type.
Defer the ID construction to the interface function.

All FS API objects have now been removed from FSX internal structures.

* subversion/libsvn_fs_x/fs.h
  (change_t): Switch ID type.

* subversion/libsvn_fs_x/temp_serializer.c
  (serialize_change,
   deserialize_change): One less sub-structure to (de-)serialize.

* subversion/libsvn_fs_x/low_level.c
  (read_change,
   write_change_entry): Use the appropriate parser / writer functions.

* subversion/libsvn_fs_x/changes.c
  (binary_change_t): The node-ID is no longer needed.
  (append_change,
   svn_fs_x__changes_get_list): No ID conversion necessary anymore.
  (svn_fs_x__write_changes_container,
   svn_fs_x__read_changes_container): One sub-struct less to store / load.
  (svn_fs_x__changes_get_list_func): No ID conversion necessary anymore.

* subversion/libsvn_fs_x/transaction.c
  (path_change_dup): ID doesn't require a manual copy anymore.
  (fold_change): Update ID checks.
  (svn_fs_x__add_change): Don't convert the ID here.

* subversion/libsvn_fs_x/tree.c
  (construct_fs_path_change): Implement the ID conversion here. The node-ID
                              lookup here is only temporary and will soon
                              become unnecessary. 
  (x_paths_changed): Update caller.

git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/fsx-id@1648094 13f79535-47bb-0310-9956-ffa450edef68