D3D12: Some fixes including stuff for GL 3.3
This series
- enables the CAP VERTEX_ELEMENT_INSTANCE_DIVISOR which enables ARB_instanced_arrays needed for GL 3.3
- sets the maximum number of varyings according to the DX11 spec (I didn't find the infor for DX12)
- fixes lowering of int texture sampling for non-fragment shaders, because here CalculateLOD is not available I'm not sure whether CL kernels support CalculateLOD, so maybe that patch needs a tweak there (for that reason WIP)
Edited by Gert Wollny