Test chasing aliases to referrals

In RFC 8499, the definition for “referral” mentions an example of a DNS response containing both a non-empty answer section and a non-empty authority section. However, the case where such responses may be generated was not tested.

Fortunately, it’s easily reproduced by creating an alias pointing to a name inside a zone delegated to a different set of name servers. Fortunately also, IBDNS already does the right thing.