Extend nss-nonlocal to support whitelisting nonlocal groups and grplists

[andersk]

   debathena / nss-nonlocal / quentin  16:56  (Quentin Smith)
       I need the users to have local home directories. I can't add the
       nonlocal groups to the local users because then remote users won't
       appear in the remote groups, thanks to nss_nonlocal.
   debathena / nss-nonlocal / andersk  17:03  (Anders Kaseorg)
       I can think of two improvements we might make:
   
       1. Adding a local user to the nss-nonlocal-users group could allow
       them to be added to nonlocal groups.
   
       2. We could make an nss-nonlocal-users user, such that adding it to a
       local group causes nonlocal users to be added to the group.

[andersk]

I’m working on implementing this on the  nss_nonlocal.git whitelist branch. Currently (1) should work.

[andersk]

(1) and (2) are implemented on the  nss_nonlocal.git whitelist branch, along with some other cleanup. I’ll plan on releasing this as nss_nonlocal 2.0, modulo any feedback.