re-done all of samr_query_disp_info()

re-done all of samr_query_disp_info()
instead of enumerating the whole user db or group db every time, we store
a in memory copy linked to the handle.

that's much faster for large enumeration where the db can't fit in a
single rpc packet. And as it's a copy, it's constant between enumeration.

still some stuff to clean. But now I can fix the W95 userlist bug, as I've
finally found it.

	J.F.
(This used to be commit 3ab45215369e8e93d750f4687e9c1f7d47782590)