Skip move-related checks and updates in FSFS if moves are not supported.
This minimizes the overhead for existing repositories.

* subversion/libsvn_fs_fs/transaction.c
  (write_final_changed_path_info,
   commit_body): execute fs_move related code only if moves are supported
                 by the current FSFS format


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1527217 13f79535-47bb-0310-9956-ffa450edef68