Add codegen files for walls and columns

src/r_compiler/fixedfunction/drawcolumncodegen.h

@@ -0,0 +1,26 @@
+
+#pragma once
+
+#include "drawercodegen.h"
+
+enum class DrawColumnVariant
+{
+	Opaque,
+	Fuzz,
+	Add,
+	Translated,
+	TlatedAdd,
+	Shaded,
+	AddClamp,
+	AddClampTranslated,
+	SubClamp,
+	SubClampTranslated,
+	RevSubClamp,
+	RevSubClampTranslated
+};
+
+class DrawColumnCodegen : public DrawerCodegen
+{
+public:
+	void Generate(DrawColumnVariant variant, SSAValue args);
+};