Fix some arm disassembly stuff

Some random code which is trying to align columns or something gets pooped up because "BLX" has no second part

src/BizHawk.Emulation.Cores/CPUs/ARM/Darm.cs

@@ -101,7 +101,7 @@ namespace BizHawk.Emulation.Cores.Components.ARM
 			string[] ret = Encoding.ASCII.GetString(s.total, 0, Array.IndexOf(s.total, (byte)0))
 				.ToString()
 				.Split(new string[] {" "}, 2, StringSplitOptions.None);
-			return ret[0].PadRight(8) + ret[1];
+			return ret[0].PadRight(8) + (ret.Length > 1 ? ret[1] : "");
 		}
 	}