Static macro methods on @:generic classes

[Simn]

@:generic
class Main<T> {
    static function main() {
        new Main<String>();
    }

    function new() { }

    macro static function test() {
        return macro null;
    }
}

This currently errors with src/Main.hx:3: lines 3-5 : A generic class can't have static fields. For one the error position is off, but I don't really see why we have to disallow macros on @:generic classes in the first place.

This likely means using load_type_def instead of load_instance in load_macro, but that strikes me as the better approach anyway as we don't actually need a TInst there.