s4:subtree_rename LDB module - fix the move/rename constraints

s4:subtree_rename LDB module - fix the move/rename constraints

s4:subtree_rename LDB module - fix the move/rename constraints

By the inspiration of an email request by ekacnet I have rechecked the
move/rename constraints and re-read the chapter 3.1.1.5.4.1 located in the
MS-ADTS technical documentation.
It really turns out that the constraint checking is only performed on
the root object of a request.

In addition add my copyright notice (I've written these constraint checks).

Autobuild-User: Matthieu Patou <mat@samba.org>
Autobuild-Date: Wed Aug 10 01:05:19 CEST 2011 on sn-devel-104