[PATCH] knfsd: allow the server to provide a gid list when using AUTH_UNIX authentication

AUTH_UNIX authentication (the standard with NFS) has a limit of 16 groups ids.
 This causes problems for people in more than 16 groups.

So allow the server to map a uid into a list of group ids based on local
knowledge rather depending on the (possibly truncated) list from the client.

If there is no process on the server responding to upcalls, the gidlist in the
request will still be used.

Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>