CoreTiming: Move static variables into Core::System.

Source/Core/Core/System.h

@@ -14,8 +14,9 @@ class AudioInterfaceState;
 };
 namespace CoreTiming
 {
+class CoreTimingState;
 struct Globals;
-}
+}  // namespace CoreTiming
 namespace DSP
 {
 class DSPState;
@@ -80,6 +81,7 @@ public:
   void SetAudioDumpStarted(bool started);
 
   AudioInterface::AudioInterfaceState& GetAudioInterfaceState() const;
+  CoreTiming::CoreTimingState& GetCoreTimingState() const;
   CoreTiming::Globals& GetCoreTimingGlobals() const;
   DSP::DSPState& GetDSPState() const;
   DVDInterface::DVDInterfaceState& GetDVDInterfaceState() const;