r21878: Fix a bug with smbd serving a windows terminal server: If winbind decides...

r21878: Fix a bug with smbd serving a windows terminal server: If winbind decides smbd
to be idle it might happen that smbd needs to do a winbind operation (for
example sid2name) as non-root. This then fails to get the privileged
pipe. When later on on the same connection another authentication request
comes in, we try to do the CRAP auth via the non-privileged pipe.

This adds a winbindd_priv_request_response() request that kills the existing
winbind pipe connection if it's not privileged.

Volker