New command-line option in Plink (and PuTTY, though it's less useful

there): `plink host -nc host2:port' causes the SSH connection's main
channel to be replaced with a direct-tcpip connection to the
specified destination. This feature is mainly designed for use as a
local proxy: setting your local proxy command to `plink %proxyhost
-nc %host:%port' lets you tunnel SSH over SSH with a minimum of
fuss. Works on all platforms.

[originally from svn r6823]

windows/winplink.c

@@ -502,7 +502,7 @@ int main(int argc, char **argv)
 	cfg.host[p1] = '\0';
     }
 
-    if (!cfg.remote_cmd_ptr && !*cfg.remote_cmd)
+    if (!cfg.remote_cmd_ptr && !*cfg.remote_cmd && !*cfg.ssh_nc_host)
 	flags |= FLAG_INTERACTIVE;
 
     /*