idmap: return the correct id type to *id_to_sid methods

idmap: return the correct id type to *id_to_sid methods

We have a pointer to a unixid which is sent down instead of a uid or
gid. We can use this as an in-out variable so that pdb_samba_dsdb can be
returned ID_TYPE_BOTH to cache correctly instead of leaving it as
ID_TYPE_UID or ID_TYPE_GID.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=10720

Change-Id: I0cef2e419cbb337531244b7b41c708cf2ab883e3
Signed-off-by: Garming Sam <garming@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Stefan Metzmacher <metze@samba.org>