Remove legacy SOCKS5 phase 1 code

  switch (socksver) { /* which version of socks? */

    case 5: /* socks5 */

      if (req->socks_version != 5) { /* we need to negotiate a method */

        unsigned char nummethods = (unsigned char)*(data+1);

        int have_user_pass, have_no_auth;

        int r=0;

        tor_assert(!req->socks_version);

        if (datalen < 2u+nummethods) {

          *want_length_out = 2u+nummethods;

          return 0;

        }

        if (!nummethods)

          return -1;

        req->replylen = 2; /* 2 bytes of response */

        req->reply[0] = 5; /* socks5 reply */

        have_user_pass = (memchr(data+2, SOCKS_USER_PASS, nummethods) !=NULL);

        have_no_auth   = (memchr(data+2, SOCKS_NO_AUTH,   nummethods) !=NULL);

        if (have_user_pass && !(have_no_auth && req->socks_prefer_no_auth)) {

          req->auth_type = SOCKS_USER_PASS;

          req->reply[1] = SOCKS_USER_PASS; /* tell client to use "user/pass"

                                              auth method */

          req->socks_version = 5; /* remember we've already negotiated auth */

          log_debug(LD_APP,"socks5: accepted method 2 (username/password)");

          r=0;

        } else if (have_no_auth) {

          req->reply[1] = SOCKS_NO_AUTH; /* tell client to use "none" auth

                                            method */

          req->socks_version = 5; /* remember we've already negotiated auth */

          log_debug(LD_APP,"socks5: accepted method 0 (no authentication)");

          r=0;

        } else {

          log_warn(LD_APP,

                    "socks5: offered methods don't include 'no auth' or "

                    "username/password. Rejecting.");

          req->reply[1] = '\xFF'; /* reject all methods */

          r=-1;

        }

        /* Remove packet from buf. Some SOCKS clients will have sent extra

         * junk at this point; let's hope it's an authentication message. */

        *drain_out = 2u + nummethods;

        return r;

      }

      if (req->auth_type != SOCKS_NO_AUTH && !req->got_auth) {

        log_warn(LD_APP,

                 "socks5: negotiated authentication, but none provided");