dontdiff: update with Kconfig build artifacts

Add generated *conf-cfg files.

Commit 694c49a7

 ("kconfig: drop localization support") removed
"gconf.glade.h" and "kxgettext".

"kconfig" and "lxdialog" should not be excluded either.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>