Add missing import

fixes 9e9e041bb

src/BizHawk.Client.EmuHawk/CustomControls/InputRoll/InputRoll.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.ComponentModel;
+using System.Diagnostics;
 using System.Drawing;
 using System.Linq;
 using System.Windows.Forms;