default IPv6 exit policy missing

Summary

Steps to reproduce:

1. create torrc exit configuration
2. notice that IPv4 default exit policy is applied, but IPv6 exit policy is missing

What is the current bug behavior?

IPv6 default exit policy is missing

What is the expected behavior?

Have a default IPv6 exit restriction policy, like for IPv4.

E.g. the following should be rejected by default:

::1/128

fe80::/10

fec0::/10

fc00::/7

All IPv6 addresses that are assigned to the host, dunno how that is handled for IPv4, should be rejected too.

If that is missing TOR exits can be used to circumvent firewalls, as they normally do not filter loopback traffic.

Rejecting multicast (ff00::/8 and 224.0.0.0/4 should be clarified.