Fix: assert conn->fd typo

Signed-off-by: David Goulet <dgoulet@ev0ke.net>
Fix: IPv6 typo in socks5_send_resolve_ptr_request

Signed-off-by: David Goulet <dgoulet@ev0ke.net>
Fix: change socks5_send_ptr_request to use address type

inet_ntop returns a pointer to the destination string, so an IPv6
address would always be converted as if it were an IPv4 address
(AF_INET).

Add the address family as a third parameter to socks5_send_ptr_request
to reliably determine the address type to request. The order of
parameters to socks5_send_ptr_request has also been changed.

Signed-off-by: David Goulet <dgoulet@ev0ke.net>