delete redundant '__send__' definition

src/kernel.c

@@ -1111,7 +1111,6 @@ mrb_init_kernel(mrb_state *mrb)
   mrb_define_method(mrb, krn, "remove_instance_variable",   mrb_obj_remove_instance_variable,ARGS_REQ(1));    /* 15.3.1.3.41 */
   mrb_define_method(mrb, krn, "respond_to?",                obj_respond_to,                  ARGS_ANY());     /* 15.3.1.3.43 */
   mrb_define_method(mrb, krn, "send",                       mrb_f_send,                      ARGS_ANY());     /* 15.3.1.3.44 */
-  mrb_define_method(mrb, krn, "__send__",                   mrb_f_send,                      ARGS_ANY());     /* 15.3.1.3.4 */
   mrb_define_method(mrb, krn, "singleton_methods",          mrb_obj_singleton_methods_m,     ARGS_ANY());     /* 15.3.1.3.45 */
   mrb_define_method(mrb, krn, "to_s",                       mrb_any_to_s,                    ARGS_NONE());    /* 15.3.1.3.46 */