D3D12: Additions to VideoCommon to support D3D12 backend.

Source/Core/VideoCommon/VertexLoaderManager.h

@@ -5,19 +5,25 @@
 #pragma once
 
 #include <string>
+#include <unordered_map>
 
 #include "Common/CommonTypes.h"
 
 class DataReader;
 class NativeVertexFormat;
+struct PortableVertexDeclaration;
 
 namespace VertexLoaderManager
 {
+	using NativeVertexFormatMap = std::unordered_map<PortableVertexDeclaration, std::unique_ptr<NativeVertexFormat>>;
+
 	void Init();
 	void Shutdown();
 
 	void MarkAllDirty();
 
+	NativeVertexFormatMap* GetNativeVertexFormatMap();
+
 	// Returns -1 if buf_size is insufficient, else the amount of bytes consumed
 	int RunVertices(int vtx_attr_group, int primitive, int count, DataReader src, bool skip_drawing, bool is_preprocess);