[4.2] Route : provides HEAD when GET is set in Route::match()

This ensures that `HEAD` method is also taken in consideration when `GET` method is set in `Route::match()`.

This way, these two routes declarations also provide a `HEAD` method.

```php
Route::get('foo', function() { return 'bar'; });
Route::match(['GET'], 'foo', function() { return 'bar'; });
```
Don't change this. I like to keep it explicit here. Less digging.