We already copy to a temp, so just use that copy to normalize out the
offset. Should even get RECT2LIN correct, but most cases are 1 pixel high
anyway.
Basically, software culling fails in some configuration, like the one we
end up with on Mali.
As noted by unknownbrackets in #15661, the viewport Z scale, offset is -0.0, 0.0.
We end up with CalcCullParams computing minZValue == maxZValue == 1.0f,
and with the vertices ending up with z,w == 1.0, 1.0.
and as a result, the inside/outside calculations will always decide that
it's outside.
Changing the comparisons from >= / <= to > / < fixes the problem, but I
don't know if this might break something else.
Anyhow, here's the simple way to repro on PC:
Change the ending of GPU_Vulkan::CheckFeatures to:
```c
return GPU_USE_LIGHT_UBERSHADER | GPU_USE_BLEND_MINMAX | GPU_USE_TEXTURE_NPOT | GPU_USE_INSTANCE_RENDERING |
GPU_USE_VERTEX_TEXTURE_FETCH | GPU_USE_TEXTURE_FLOAT | GPU_USE_16BIT_FORMATS | GPU_USE_TEXTURE_LOD_CONTROL |
GPU_USE_DEPTH_TEXTURE | GPU_USE_ACCURATE_DEPTH;
```
