On the fsx-id branch:  Always use the internal ID type for predecessors.

* subversion/libsvn_fs_x/dag.h
  (svn_fs_x__dag_get_predecessor_id): Switch ID type and drop unused pool.

* subversion/libsvn_fs_x/dag.c
  (svn_fs_x__dag_get_predecessor_id): Simplify implementation.

* subversion/libsvn_fs_x/tree.c
  (x_closest_copy,
   history_prev,
   verify_node,
   svn_fs_x__verify_root): Update callers.


git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/fsx-id@1647761 13f79535-47bb-0310-9956-ffa450edef68