Speed up SslStream initialization a bit

            stream: stream,

            ssl: Arc::new(ssl),

            // Maximum TLS record size is 16k

            buf: Vec::from_elem(16 * 1024, 0u8)

            // We're just using this as a buffer, so there's no reason to pay

            // to memset it

            buf: {

                const CAP: uint = 16 * 1024;

                let mut v = Vec::with_capacity(CAP);

                unsafe { v.set_len(CAP); }

                v

            }

        }

    }