Refuse attempts to resolve tree conflicts with --accept=theirs-conflict.

Doing so used to break moves. But so does --accept=working and it is
confusing to have two different --accept arguments with the same effect.
And we'll probably want to use 'theirs-conflict' for some smarter resolution
strategy in some future release of Subversion.

* subversion/libsvn_wc/conflicts.c
  (resolve_tree_conflict_on_node): Stop accepting both 'theirs-conflict'
   and 'working' resolutions for breaking moves. Accept only 'working'.

* subversion/tests/cmdline/move_tests.py
  (build_simple_file_move_tests): Adjust test expectations accordingly.

* subversion/tests/cmdline/update_tests.py
  (break_moved_dir_edited_leaf_del): Adjust test expectations.



git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1449761 13f79535-47bb-0310-9956-ffa450edef68