Fixes the timer returning 1 when it should return 0. The case mentioned by the comment does not exist anymore.

Also added a IsRunning function as it was impossible to know whether it had been started or not (I will use it in later PRs but it should be there anyway)

Source/Core/Common/Timer.h

@@ -23,6 +23,8 @@ public:
   u64 GetTimeDifference();
   void AddTimeDifference();
 
+  bool IsRunning() const { return m_Running; }
+
   static void IncreaseResolution();
   static void RestoreResolution();
   static u64 GetTimeSinceJan1970();