Fix permission evaluation for !new_style ACLs

Fix permission evaluation for !new_style ACLs

	* security.h (authz_get_user_attribute): Declare bool.
	* sec_helper.cc (authz_ctx::get_user_attribute): Make bool method.
	Set S_IxOTH bits in returned attributes rather than S_IxUSR bits.
	(authz_get_user_attribute): Make bool function.
	* sec_acl.cc (get_posix_access): Introduce cygsid array to keep
	track of all SIDs in the ACL.  Move AuthZ calls into !new_style
	permission post processing.  When not using AuthZ, use
	CheckTokenMembership to collect group permissions.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>