VideoCommon: keep a copy of the const buffer in VideoCommon

The upload in the backend isn't done, it's just pushed by the mostly removed SetMulti*SConstant4fv.
Also no optimizations was done on VideoCommon side, but I can start now :-)

Sorry for the hacky way, but I think this is a nice (working) snapshot for a much bigger change.

Source/Core/VideoCommon/Src/PixelShaderManager.h

@@ -8,9 +8,12 @@
 #include "BPMemory.h"
 #include "XFMemory.h"
 #include "PixelShaderGen.h"
+#include "ConstantManager.h"
 
 class PointerWrap;
 
+
+
 // The non-API dependent parts.
 class PixelShaderManager
 {
@@ -41,6 +44,9 @@ public:
 	static void SetColorMatrix(const float* pmatrix);
 	static void InvalidateXFRange(int start, int end);
 	static void SetMaterialColorChanged(int index);
+	
+	static PixelShaderConstants constants;
+	static bool dirty;
 };