Support for doing DNS at the proxy end. I've invented a new type of

SockAddr, which just contains an unresolved hostname and is created
by a stub function in *net.c. It's an error to pass this to most of
the real-meat functions in *net.c; these fake addresses should have
been dealt with by the time they get down that far. proxy.c now
contains name_lookup(), a wrapper on sk_namelookup() which decides
whether or not to do real DNS, and the individual proxy
implementations each deal sensibly with being handed an unresolved
address and avoid ever passing one down to *net.c.

[originally from svn r2353]

telnet.c

@@ -678,7 +678,7 @@ static char *telnet_init(void *frontend_handle, void **backend_handle,
 	logevent(telnet->frontend, buf);
 	sfree(buf);
     }
-    addr = sk_namelookup(host, realhost);
+    addr = name_lookup(host, port, realhost);
     if ((err = sk_addr_error(addr)))
 	return err;