fix mrb_funcall calling

mrbgems/mruby-struct/src/struct.c

@@ -381,7 +381,7 @@ mrb_struct_s_def(mrb_state *mrb, mrb_value klass)
   }
   st = make_struct(mrb, name, rest, struct_class(mrb));
   if (!mrb_nil_p(b)) {
-    mrb_funcall(mrb, b, "call", 1, &st);
+    mrb_funcall(mrb, b, "call", 1, st);
   }
 
   return st;

src/hash.c

@@ -18,7 +18,7 @@ mrb_hash_ht_hash_func(mrb_state *mrb, mrb_value key)
   khint_t h = (khint_t)mrb_type(key) << 24;
   mrb_value h2;
 
-  h2 = mrb_funcall(mrb, key, "hash", 0, 0);
+  h2 = mrb_funcall(mrb, key, "hash", 0);
   h ^= h2.value.i;
   return h;
 }

src/object.c

@@ -588,7 +588,7 @@ mrb_Float(mrb_state *mrb, mrb_value val)
 mrb_value
 mrb_inspect(mrb_state *mrb, mrb_value obj)
 {
-  return mrb_obj_as_string(mrb, mrb_funcall(mrb, obj, "inspect", 0, 0));
+  return mrb_obj_as_string(mrb, mrb_funcall(mrb, obj, "inspect", 0));
 }
 
 mrb_bool