change 1077. introduced a locking hierarchy violation; fix by introducing a separate lock for resolver->nfctx.
change 1077. introduced a locking hierarchy violation; fix by
introducing a separate lock for resolver->nfctx.

pecharmin/bind9,pecharmin/bind9,each/bind9-collab,pecharmin/bind9,each/bind9-collab,pecharmin/bind9,pecharmin/bind9,each/bind9-collab,each/bind9-collab,pecharmin/bind9,each/bind9-collab,each/bind9-collab