Fix the core of the SAMR access functions. This passes make test, but

Fix the core of the SAMR access functions. This passes make test, but
usrmgr fails against it. The core of this patch is to move all the
access mask setup into the _samr_OpenXXX functions, and then have
each specific function check the attached access_mask against the
required bits. We can then go through the MS-SAMR doc and match
things up. Signed off by Guenther, and writespace cleanup removal
by Volker.
Jeremy.
(cherry picked from commit bdc797135151d4f85e6368d016bfb26389c6f055)