rwrap: Recursively add additional data

Change how we construct the fake answer such that the header and
question are added first, then the answers and finally additional data.

Signed-off-by: Jakub Hrozek <jakub.hrozek@gmail.com>
tests: test that CNAME and SRV records can recurse

Add tests for recursing into a CNAME record.

Signed-off-by: Jakub Hrozek <jakub.hrozek@gmail.com>
rwrap: Support asking for A via CNAME

Adds support for querying for an A record using a name that only expands
into a CNAME.

Signed-off-by: Jakub Hrozek <jakub.hrozek@gmail.com>
tests: Query A record via CNAME

Signed-off-by: Jakub Hrozek <jakub.hrozek@gmail.com>