-- v7: vkd3d-shader/dxil: Implement DX instruction LoadInput. vkd3d-shader/dxil: Declare shader inputs. vkd3d-shader/dxbc: Load input signatures also from ISG1 chunks. vkd3d-shader/spirv: Build undefined values once. vkd3d-shader/spirv: Introduce a Static Single Assignment register type.