Add missing arch.h file

include/arch.h

+#ifndef ARCH_H
+#define ARCH_H
+
+class Arch {
+	private:
+		Arch(const Arch &copy);
+
+	public:
+		Arch () {}
+		void setup();
+		void idle_loop();
+};
+
+extern Arch arch;
+
+#endif