s3:winbind: Fix the talloc hierarchy in wb_queryuser_done

s3:winbind: Fix the talloc hierarchy in wb_queryuser_done

We need to return state->userinfo beyond the end of wb_queryuser_recv, so the
unmarshalled strings are children of that, not the state that is lost sooner.

Metze, this scheme works fine as long as we only have a single malloc'ed
entity that is returned. I think we need a different scheme in the future
when we might have more than one independent object to be returned.