gl_rasterizer: Implement texture format ASTC_2D_4X4.

src/video_core/textures/astc.h

@@ -0,0 +1,15 @@
+// Copyright 2018 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <cstdint>
+#include <vector>
+
+namespace Tegra::Texture::ASTC {
+
+std::vector<uint8_t> Decompress(std::vector<uint8_t>& data, uint32_t width, uint32_t height,
+                                uint32_t block_width, uint32_t block_height);
+
+} // namespace Tegra::Texture::ASTC