extending nss and examples/nss a bit

[Luke Howard]

>Once you do this I think it is fairly natural to start extending nss
>within the spirit of the nss framework of calls. The nss_sidtoname()
>is the obvious syntax in keeping with the other standard nss calls,
>and I think would be quite a sane extension to actually add to the nss
>standard at some stage. While at the moment the call is only available
>via dlopen() I hope that it will eventually be available in glibc and
>other C libraries to provide a much better degree of interoperability
>with the MS world.

We can add similar functions to nss_ldap, too. But it would be useful to
discuss the API at least at a high level with the appropriate glibc folk
(Ulrich was the last person who let me add an NSS interface about six
years ago -- the getaliasbyname() stuff which came from NEXTSTEP :-)).

-- Luke