Family mismatch on dual stack environments breaks whitelist

[TomCan]

In dual stack environments, r->useragent_addr might return an IPv4 mapped IPv6 address instead of a regular IPv4 address. In that case, apr_sockaddr_t->family will return AF_INET6 instead of AF_INET and will not take any IPv4 entries on the whitelist into account. This can results in whitelisted IPv4 address to be blocked anyway.

This PR solves this by adding additional checks to see if this is in fact an IPv4 mapped IPv6 address, and adjusts the matching logic accordingly.