In connection_ap_handshake_process_socks(), mark the socks request as finished...

In connection_ap_handshake_process_socks(), mark the socks request as finished if a reply is send after a parse error

Silences the log message:
[warn] {BUG} _connection_mark_unattached_ap(): Bug: stream (marked at connection_edge.c:2224) sending two socks replies?
after the client triggered the "Tor is not an HTTP Proxy" response.

No additional socks reply was sent, though.