GPU: Implement interlaced rendering in hardware backends

src/core/gpu_hw_shadergen.h

@@ -13,7 +13,7 @@ public:
 
   std::string GenerateBatchVertexShader(bool textured);
   std::string GenerateBatchFragmentShader(GPU_HW::BatchRenderMode transparency, GPU::TextureMode texture_mode,
-                                          bool dithering);
+                                          bool dithering, bool interlacing);
   std::string GenerateBatchLineExpandGeometryShader();
   std::string GenerateScreenQuadVertexShader();
   std::string GenerateFillFragmentShader();