Comment out unused field

was assigned to before refactor in fc92d3c63

src/BizHawk.Client.EmuHawk/tools/Debugger/GenericDebugger.Disassembler.cs

@@ -140,10 +140,10 @@ namespace BizHawk.Client.EmuHawk
 			}
 		}
 
-		private bool _blockScroll;
+//		private bool _blockScroll;
 		private void DisassemblerView_Scroll(object sender, EventArgs e)
 		{
-			if (_blockScroll) { return; }
+//			if (_blockScroll) { return; }
 
 			// is this still needed?
 		}