Cleanup SERVER struct

Removed one unused field. Rearranged others, clarified comments.

server/modules/authenticator/GSSAPI/GSSAPIBackendAuth/gssapi_backend_auth.c

@@ -150,7 +150,7 @@ bool extract_principal_name(DCB *dcb, GWBUF *buffer)
          * it's possible that the server authenticated us as the anonymous user. This
          * means that the server is not secure. */
         MXS_ERROR("Server '%s' returned an unexpected authentication response.%s",
-                  dcb->server->unique_name, databuf[0] == MYSQL_REPLY_OK ?
+                  dcb->server->name, databuf[0] == MYSQL_REPLY_OK ?
                   " Authentication was complete before it even started, "
                   "anonymous users might not be disabled." : "");
         return false;