libcli: Add security_token_system_privilege().

Signed-off-by: Andreas Schneider <asn@samba.org>
Reviewed-by: Günther Deschner <gd@samba.org>
s3-rpc_server: Grant the system token full access.

Signed-off-by: Andreas Schneider <asn@samba.org>
Reviewed-by: Günther Deschner <gd@samba.org>
s3-netlogon: Connecting with the system token should be sufficient.

Signed-off-by: Andreas Schneider <asn@samba.org>
Reviewed-by: Günther Deschner <gd@samba.org>

Autobuild-User(master): Günther Deschner <gd@samba.org>
Autobuild-Date(master): Tue Aug  6 18:22:06 CEST 2013 on sn-devel-104