Windows: Assign AuthGroup during Process Create

Windows: Assign AuthGroup during Process Create

As the process is being created, assign the AuthGroup so that
the must up to date information is used to assign AuthGroup
inheritance from Impersonation states and to prevent the parent
process from being destroyed before the AuthGroup is determined.

Change-Id: I176360a589d7f2bcf4b1ededad069424e3ce5393
Reviewed-on: http://gerrit.openafs.org/6927
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Peter Scott <pscott@kerneldrivers.com>
Tested-by: Jeffrey Altman <jaltman@secure-endpoints.com>
Reviewed-by: Jeffrey Altman <jaltman@secure-endpoints.com>