Make DnsPort, IPv6, and AutomapHostsOnResolve work together

From legacy/trac#10465 (moved): I started Tor with "./src/or/tor -dnsport '9999 preferipv6automap' -automaphostsonresolve 1 -automaphostssuffix . "

Then I did:

[619]$ dig @localhost -p 9999 aaaa www.torproject.org

; <<>> DiG 9.8.3-P1 <<>> @localhost -p 9999 aaaa www.torproject.org
; (3 servers found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 45384
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;www.torproject.org.		IN	AAAA

;; ANSWER SECTION:
www.torproject.org.	60	IN	A	127.237.144.204

;; Query time: 0 msec
;; SERVER: 127.0.0.1#9999(127.0.0.1)
;; WHEN: Sun Dec 22 09:19:54 2013
;; MSG SIZE  rcvd: 52

and

[621]$ dig @localhost -p 9999 example.com

; <<>> DiG 9.8.3-P1 <<>> @localhost -p 9999 example.com
; (3 servers found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 18398
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;example.com.			IN	A

;; ANSWER SECTION:
example.com.		60	IN	A	127.201.101.133

;; Query time: 0 msec
;; SERVER: 127.0.0.1#9999(127.0.0.1)
;; WHEN: Sun Dec 22 09:20:31 2013
;; MSG SIZE  rcvd: 45

It seems to be sending A even if it was asked for an AAAA.

(There are deeper DNSPort+IPv6 issues going on, of course, but this part is probably easier, and it's an independently useful bit of functionality.)

See legacy/trac#10465 (moved) notes for more