SwRasterizer/Lighting: move to its own file

src/video_core/swrasterizer/fragment_lighting.h

@@ -0,0 +1,18 @@
+// Copyright 2017 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <tuple>
+#include "common/quaternion.h"
+#include "common/vector_math.h"
+#include "video_core/pica_state.h"
+
+namespace Pica {
+
+std::tuple<Math::Vec4<u8>, Math::Vec4<u8>> ComputeFragmentsColors(
+    const Pica::LightingRegs& lighting, const Pica::State::Lighting& lighting_state,
+    const Math::Quaternion<float>& normquat, const Math::Vec3<float>& view);
+
+} // namespace Pica