Fixed Missing DoFrame Call

Somewhere in the process of getting the memory peeking right for achievements, the AchievementManager call to DoFrame went missing. This restores it properly.

Source/Core/Core/Core.cpp

@@ -900,6 +900,10 @@ void Callback_NewField(Core::System& system)
       CallOnStateChangedCallbacks(Core::GetState());
     }
   }
+
+#ifdef USE_RETRO_ACHIEVEMENTS
+  AchievementManager::GetInstance()->DoFrame();
+#endif  // USE_RETRO_ACHIEVEMENTS
 }
 
 void UpdateTitle()