Static macro methods on @:generic classes

[fussybeaver]

This is a regression from a previous fix: #3766

Example:

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

    function new() { }

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

This fails to compile with the error "A generic class can't have static fields"

Macro static methods are an exception, and are allowed in a generic class https://github.com/HaxeFoundation/haxe/blob/3.2.1/codegen.ml#L418

[Simn]

This one confused me, but there's no regression here:

1. Your example is invalid because you do in fact have the static function main on your @:generic class.
2. You have to #if !macro your macro function, the error you're getting actually occurs in macro context because there the macro is not really considered a macro (don't ask).