Add debugging for GPU/Timers

src/core/timers.h

@@ -20,6 +20,9 @@ public:
 
   void SetGate(u32 timer, bool state);
 
+  void DrawDebugMenu();
+  void DrawDebugWindow();
+
   // dot clock/hblank/sysclk div 8
   bool IsUsingExternalClock(u32 timer) const { return m_states[timer].external_counting_enabled; }
   void AddTicks(u32 timer, TickCount ticks);
@@ -78,4 +81,6 @@ private:
 
   std::array<CounterState, NUM_TIMERS> m_states{};
   u32 m_sysclk_div_8_carry = 0;   // partial ticks for timer 3 with sysclk/8
+
+  bool m_debug_show_state = false;
 };