test: check if the large response has the TC bit set
test: check if the large response has the TC bit set

Note we parse only the DNS details because if the packet is truncated
then `Dns.Protocol.Server.parse` will raise an exception (unhelpfully)

Signed-off-by: David Scott <63c9eb0ea83039690fefa11afe17873ba8278a56@docker.com>

djs55/vpnkit,djs55/vpnkit,djs55/vpnkit