A64: Hardwire the decoder and the simulator

src/a64/decoder-a64.h

Index: src/a64/decoder-a64.h
diff --git a/src/a64/decoder-a64.h b/src/a64/decoder-a64.h
index 8ad6b44b119e7a2c571bbd55bd5f2eabbc83c04c..22a7e3547bed232672af16a5a66e3b36344e977e 100644
--- a/src/a64/decoder-a64.h
+++ b/src/a64/decoder-a64.h
@@ -146,10 +146,11 @@ template<typename V>
 class Decoder : public V {
  public:
   Decoder() {}
+  virtual ~Decoder() {}
 
   // Top-level instruction decoder function. Decodes an instruction and calls
   // the visitor functions registered with the Decoder class.
-  void Decode(Instruction *instr);
+  virtual void Decode(Instruction *instr);
 
  private:
   // Decode the PC relative addressing instruction, and call the corresponding