Move-updating can only raise a tree-conflict if no obstructing
tree-conflict exists.

* subversion/libsvn_wc/wc_db_update_move.c
  (mark_tree_conflict): Remove skel parameter, always check existing conflict.
  (check_tree_conflict): Move existing conflict code to mark_tree_conflict.
  (tc_editor_add_directory, tc_editor_add_file, tc_editor_delete,
   resolve_delete_raise_moved_away): Don't pass NULL skel.

* subversion/tests/libsvn_wc/op-depth-test.c
  (layered_moved_to): Extend to test failure to resolve.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1442610 13f79535-47bb-0310-9956-ffa450edef68