incorrect top-scope variable warning for define

puppet-lint gives the error "top-scope variable being used without an explicit namespace" for the first three parameters; no warning is given if they have default values provided.

```
define tomcat::base (
    $initial_heap,
    $max_heap,
    $max_perm_gen,
    $owner = hiera('app_user'),
    $classpath = [],
    $enable_manager = false,
    $system_properties = {},
) { … }
```