On the fsx-id branch:  Split off the FS API ID implementation from the
id.* files that will henceforth only contain the internal ID handling.

* subversion/libsvn_fs_x/fs_id.h
  (svn_fs_x__id_create): The only function we keep here. 

* subversion/libsvn_fs_x/fs_id.c
  (fs_x__id_t): Move here.
  (id_unparse): Same; reimplement using functions from id.h.
  (id_compare,
   id_vtable,
   svn_fs_x__id_create): Move here.

* subversion/libsvn_fs_x/id.h
  (svn_fs_x__id_create): Remove here.

* subversion/libsvn_fs_x/id.c
  (fs_x__id_t,
   id_unparse,
   id_compare,
   id_vtable,
   svn_fs_x__id_create): Remove here.

* subversion/libsvn_fs_x/tree.c
* subversion/libsvn_fs_x/dag.c
  (): Update #includes.

git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/fsx-id@1648108 13f79535-47bb-0310-9956-ffa450edef68