fix: src\class.c(949): warning C4244: '=': conversion from 'mrb_int' to 'int',...

fix: src\class.c(949): warning C4244: '=': conversion from 'mrb_int' to 'int', possible loss of data

src/class.c

@@ -570,7 +570,7 @@ mrb_get_args(mrb_state *mrb, const char *format, ...)
   mrb_int i = 0;
   va_list ap;
   mrb_int argc = mrb->c->ci->argc;
-  int arg_i = 0;
+  mrb_int arg_i = 0;
   mrb_value *array_argv;
   mrb_bool opt = FALSE;
   mrb_bool opt_skip = TRUE;