Make the tree conflict resolver smart enough to retry resolving tree conflicts
again after resolving other tree conflicts when it can't be resolved because
another tree conflict is in its way.

This resolves several unwanted SVN_ERR_WC_CONFLICT_RESOLVER_FAILURE errors
during depth infinity resolving on a tree.

This resolves three more op-depth tests.

* subversion/libsvn_wc/conflicts.c
  (resolve_tree_conflict_on_node): Add argument to capture retry nodes.
    Properly set did_resolve in cases where it used to forget.
  (conflict_status_walker_baton): Add variable.
  (conflict_status_walker): Update caller. Handle not resolving of tree
    conflicts properly. Specialize error code.
  (svn_wc__resolve_conflicts): Add closure handling on tree conflicts within
    range to allow resolving all move conflicts within a tree to a specific
    state.

* subversion/libsvn_wc/wc_db_update_move.c
  (mark_tree_conflict): Return specialized error for the conflict handler
    when there is an existing tree conflict when installing.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1538707 13f79535-47bb-0310-9956-ffa450edef68
* subversion/tests/libsvn_wc/op-depth-test.c
  (test_funcs): Following up on r1538707, remove XFail marker from three tests.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1538708 13f79535-47bb-0310-9956-ffa450edef68