Following up on r1550848 and r1550938, automatically anchor the mtcc handling
on an ancestor when that is needed for certain operations.

* subversion/include/svn_client.h
  (svn_client_mtcc_get_relpath): Remove function.
  (svn_client_mtcc_check_path): Add argument.

* subversion/libsvn_client/mtcc.c
  (svn_client_mtcc_get_relpath): Rename to ...
  (mtcc_reparent): ... this function. Make static and make the new url
     an argument instead of calculating it.
  (mtcc_verify_create): Allow creating the "" path if there is no operation
     recorded yet. Update caller.

  (svn_client_mtcc_add_add_file,
   svn_client_mtcc_add_delete,
   svn_client_mtcc_add_mkdir,
   svn_client_mtcc_add_propset,
   svn_client_mtcc_add_update_file): Support adding "" when no operation is
     recorded yet.

  (svn_client_mtcc_check_path): Allow verifying the recorded node kind with
     the repository kind.

* subversion/libsvn_client/mtcc.h
  (svn_client_mtcc_op_t): Add boolean.
  (MTCC_UNMODIFIED): New macro.

* subversion/tests/libsvn_client/mtcc-test.c
  (cstr_stream): New helper function.
  (make_greek_tree,
   test_update_files): Update caller.
  (test_anchoring): New test.
  (test_funcs): Add test_anchoring.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1550940 13f79535-47bb-0310-9956-ffa450edef68