swizzling not supported on linux

on Windows, the following compiles:
```cpp
clipport.xy = glm::max(clipport.xy(), parent_vis.xy());
clipport.zw = glm::min(clipport.zw(), parent_vis.zw());
```
where `clipport` and `parent_vis` are `vec4`.

On linux, this does not work. it complains that you can't assignt to a function call.