add reset() for every platform

src/engine/platform/arcade.h

@@ -48,6 +48,7 @@ class DivPlatformArcade: public DivDispatch {
   public:
     void acquire(short* bufL, short* bufR, size_t start, size_t len);
     int dispatch(DivCommand c);
+    void reset();
     void tick();
     bool isStereo();
     int init(DivEngine* parent, int channels, int sugRate, bool pal);