add support for "proxy_dns_old" to use old 3.1 DNS lookup method

some lamer on IRC by the name of annoner/R3M0RS3/penis was complaining
that 3.1 is a lot better than proxychains-ng, because it happens to
work with the browser he's interested in.
since this wasn't the first time this is requested, let's give this
those lamers what they want: lame code!

src/core.h

@@ -121,6 +121,7 @@ struct gethostbyname_data {
 };
 
 struct hostent* proxy_gethostbyname(const char *name, struct gethostbyname_data *data);
+struct hostent* proxy_gethostbyname_old(const char *name);
 
 int proxy_getaddrinfo(const char *node, const char *service, 
 		      const struct addrinfo *hints, struct addrinfo **res);