C++ nullable comparsion problem

**Issued way**

```hx
var numb:Null = null;
if(numb != null)
{
//nullable, null comparsion not working on C++ target
trace("Something wrong with haxe: " + numb);
return;
}

trace("PASS!");
```

Javascript target returns `PASS!` but C++ target returns `Something wrong with haxe: null`

https://try.haxe.org/#c8aE5aD5

**Temporary fixed way**

```hx
var numb:Null = null;
if(Type.typeof(numb) != Type.ValueType.TNull)
{
//Null comparsion working with this way, never calls here!
trace("Something wrong with haxe: " + numb);
return;
}

trace("PASS!");
```
Javascript and C++ target returns `PASS!`

https://try.haxe.org/#58D0d884

**Platform**

OS: Windows 11
Haxe Version: 4.3.1
Hxcpp Version: 4.3.2