mrb_raisef(): new function. Same as previou version of mrb_raise().

mrb_raise(): API modified. It cannot treat variable arguments.

src/variable.c

@@ -712,7 +712,7 @@ const_get(mrb_state *mrb, struct RClass *base, mrb_sym sym)
     }
     c = c->super;
   }
-  mrb_raise(mrb, E_NAME_ERROR, "uninitialized constant %s",
+  mrb_raisef(mrb, E_NAME_ERROR, "uninitialized constant %s",
             mrb_sym2name(mrb, sym));
   /* not reached */
   return mrb_nil_value();