as discussed on irc, this is a small patch that allows a few more

as discussed on irc, this is a small patch that allows a few more
winbind functions to be accessed via NSS. This provides a much cleaner
way for applications that need (for example) to provide name->sid
mappings to do this via NSS rather than having to know the winbindd
pipe protocol (as this might change).

This patch also adds a varient of the winbindd_getgroups() call called
winbindd_getusersids() that provides direct SID->SIDs listing of a
users supplementary groups. This is enough to allow non-Samba
applications to do ACL checking.

A test program for the new functionality will be committed shortly.

I also added the 'wbinfo --user-sids' option to expose the new
function in wbinfo.