TOMOYO: Accept \000 as a valid character.

commit 25add8cf99c9ec8b8dc0acd8b9241e963fc0d29c upstream.

TOMOYO 2.5 in Linux 3.2 and later handles Unix domain socket's address.
Thus, tomoyo_correct_word2() needs to accept \000 as a valid character, or
TOMOYO 2.5 cannot handle Unix domain's abstract socket address.

Reported-by: Steven Allen <steven@stebalien.com>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: James Morris <jmorris@namei.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>