fixes to *_util.c files

fixes to *_util.c files
add winbindd_passdb backend
this makes it possible to have nua accounts on security = user servers to
show up in unic through nss_winbind.so

the problem is that we do not have group support, so nss group support is
not very good at this time (read: totally absent)

we NEED group support in passdb
(This used to be commit 921215cf4bfbd4d7457f81e181bb1a74a4531ca1)