Make 'svnadmin verify' dectect cycles in our DAG and prevent stack overflow during that check.  Found by fuzzing tests.
Make 'svnadmin verify' dectect cycles in our DAG and prevent stack overflow
during that check.  Found by fuzzing tests.

* subversion/libsvn_fs_fs/tree.c
  (verify_node): Add list of parent nodes as extra parameter and check for
                 matches with the current node, i.e. cycles.
  (svn_fs_fs__verify_root): Update caller.


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@1623398 13f79535-47bb-0310-9956-ffa450edef68

YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion