C++ "'system' : a symbol with this name already exists "

Declaring any class in a package named "system":

```
package system;
class Foo
{
    public function new() { }
}
```

Causes this error when built for the C++ target: 

```
error C2757: 'system' : a symbol with this name already exists and therefore this name cannot be used as a namespace name
```

Saw in Haxe 3.0.1