Support the RESOLVE PTR Tor command in the socks5 API

Signed-off-by: David Goulet <dgoulet@ev0ke.net>
Add IPv6 support to Tor resolve command

Signed-off-by: David Goulet <dgoulet@ev0ke.net>
Fix: set maximum possible buffer in SOCKS5 resolve req.

Signed-off-by: David Goulet <dgoulet@ev0ke.net>
Implement gethostbyname2() GNU extension call

Signed-off-by: David Goulet <dgoulet@ev0ke.net>
Implement gethostbyaddr libc call

Also add the tor resolve ptr function call in torsocks used by
gethostbyaddr().

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