No functional change.

* subversion/libsvn_fs_fs/tree.c
  (svn_fs_fs__verify_root):
    Refactor code a bit to make it easier to extend into being a non-no-op
    for txn roots.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1461693 13f79535-47bb-0310-9956-ffa450edef68