kconfig/[mn]conf: handle backspace (^H) key

Backspace is not working on some terminal emulators which do not send the
key code defined by terminfo. Terminals either send '^H' (8) or '^?' (127).
But currently only '^?' is handled. Let's also handle '^H' for those
terminals.

Signed-off-by: Changbin Du <changbin.du@gmail.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

scripts/kconfig/lxdialog/inputbox.c

@@ -113,7 +113,8 @@ do_resize:
 			case KEY_DOWN:
 				break;
 			case KEY_BACKSPACE:
-			case 127:
+			case 8:   /* ^H */
+			case 127: /* ^? */
 				if (pos) {
 					wattrset(dialog, dlg.inputbox.atr);
 					if (input_x == 0) {