[php-src] PR #23251: PFA: Fix magic method resolution

Pull Request: https://github.com/php/php-src/pull/23251 Author: arnaud-lb We conveniently use the function's scope for the scope of generated PFA closures as this allows const exprs referencing self:: or parent:: to behave normally: However this affects method resolution for magic methods: ``` class C { private static function priv($a) {} public static function __call($name, $args) {} } // Sees only C::__call() $f = C::priv(?); // Generates the following closure with scope=C: $f = function ($arguments0) { // Sees C::priv() static::priv($arguments0); }; ``` Fix by using the actual scope for PFAs of magic methods. This should be enough as long as the generated closure doesn't inherit any self:: or parent:: expression from the magic method. Currently that's the case. If this changes we may have to rewrite these expressions, which I would like to avoid as this increases complexity and maintenance overhead. The test magic_scope.phpt demonstrates the issue. default_arg_scope.phpt just checks relative-class resolution in default argument values. Bug found by Ryan @ Calif.io