Following up on r1443451, make the path stored for local-moved-away tree
conflicts no longer required for conflicts raised by merge operations.
(In other words: only required for update and switch.)

Merge doesn't have the power to look in the deeper layers of WC-NG,
nor do we intend to expose them to libsvn_client.

* subversion/include/private/svn_wc_private.h
  (svn_wc__add_tree_conflict): Update comment. Remove argument.

* subversion/libsvn_client/merge.c
  (record_tree_conflict): Update caller.

* subversion/libsvn_wc/conflicts.c
  (svn_wc__conflict_skel_add_tree_conflict): Only store moved away
    path when provided and valid for this state.
  (svn_wc__conflict_read_tree_conflict): Allow reading just the path,
    and handle move conflicts without path

* subversion/libsvn_wc/tree_conflicts.c
  (svn_wc__add_tree_conflict): Verify requirements for new in 1.8 values.
    Always pass NULL for path to svn_wc__conflict_skel_add_tree_conflict.

* subversion/tests/libsvn_wc/conflict-data-test.c
  (test_read_write_tree_conflicts): Update caller.

* tools/dev/svnraisetreeconflict/svnraisetreeconflict.c
  (raise_tree_conflict): Update caller.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1443492 13f79535-47bb-0310-9956-ffa450edef68