Implement basic performance statistics (#53)

* implement basic frame time stats

* added game frame time

* made performancestatictics class non-static

* report average framerate instead of current framerate

Ryujinx.Core/OsHle/Services/Vi/NvFlinger.cs

@@ -154,6 +154,8 @@ namespace Ryujinx.Core.OsHle.IpcServices.Android
 
         private long GbpQueueBuffer(ServiceCtx Context, BinaryReader ParcelReader)
         {
+            Context.Ns.Statistics.RecordGameFrameTime();
+
             //TODO: Errors.
             int Slot            = ParcelReader.ReadInt32();
             int Unknown4        = ParcelReader.ReadInt32();