Fix socks5 handshake for username/password auth

The fix for bug 8117 exposed this bug, and it turns out real-world
applications like Pidgin do care. Bugfix on 0.2.3.2-alpha; fixes bug 8879.

changes/bug8879

@@ -0,0 +1,5 @@
+  o Major bugfixes:
+    - Follow the socks5 protocol when offering username/password
+      authentication. The fix for bug 8117 exposed this bug, and it
+      turns out real-world applications like Pidgin do care. Bugfix on
+      0.2.3.2-alpha; fixes bug 8879.

src/or/buffers.c

@@ -1751,7 +1751,7 @@ parse_socks(const char *data, size_t datalen, socks_request_t *req,
         return 0;
       }
       req->replylen = 2; /* 2 bytes of response */
-      req->reply[0] = 5;
+      req->reply[0] = 1; /* authversion == 1 */
       req->reply[1] = 0; /* authentication successful */
       log_debug(LD_APP,
                "socks5: Accepted username/password without checking.");