scanner: Support rfc4291 IPv4-compatible addresses

scanner: Support rfc4291 IPv4-compatible addresses

These are defined in section 2.5.5.1. Although it is stated that they
are deprecated and new implementations are not required to support them,
they occur in ruleset output if an address in the form '::feed:babe' was
given in input. In order to support reinsertion of that rule, we have to
support those deprecated addresses as well.

Signed-off-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>