r13679: Commiting the rm_primary_group.patch posted on samba-technical

r13679: Commiting the rm_primary_group.patch posted on samba-technical

* ignore the primary group SID attribute from struct samu*
* generate the primary group SID strictlky from the Unix
  primary group when dealing with passdb users
* Fix memory leak in original patch caused by failing to free a
  talloc *
* add wrapper around samu_set_unix() to prevent exposing the create
  BOOL to callers.  Wrappers are samu_set_unix() and samu-allic_rid_unix()
(This used to be commit bcf269e2ec6630b78d909010fabd3b69dd6dda84)