FifoRecorder: Move instance to System.

Source/Core/VideoCommon/OpcodeDecoding.cpp

@@ -234,7 +234,7 @@ public:
       // process them.
       if (g_record_fifo_data && static_cast<Opcode>(data[0]) != Opcode::GX_CMD_CALL_DL)
       {
-        FifoRecorder::GetInstance().WriteGPCommand(data, size);
+        Core::System::GetInstance().GetFifoRecorder().WriteGPCommand(data, size);
       }
     }
   }