IrrlichtMt: Move OpenGL 3+ transformation matrix to shaders (#15591)

This replaces annoying calculations on C++-side and eases the
implementation of 2D geometry batch rendering a lot.

irr/src/OpenGL/Renderer2D.h

@@ -24,6 +24,7 @@ public:
 
 protected:
 	bool WithTexture;
+	s32 ProjectionID;
 	s32 ThicknessID;
 	s32 TextureUsageID;
 };