nss: move nss_ctx->global_names to rctx
Global names context is used to parse AD well known SIDs and names
into its opposite. This patch moves definition of this parameter
from nss responder into common responder context so it can be
used also by other responders.
This change will be use to enable looking up well known SIDs and
names directly in cache_req.
Reviewed-by: Lukáš Slebodník <lslebodn@redhat.com>