shadow: update ownership and permission of /var/spool/mail
Update shadow to change ownership of /var/spool/mail from root:root to
root:mail and permission from 0755 to 0775 just as in most popular
distributions such as fedora and debian(It also set setgid bit in debian
but we don't need it).
(From OE-Core rev:
b3ab5fe359c38cdd5cd86cb8ffe076d7a2baac18)
Signed-off-by: Kai Kang <kai.kang@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Signed-off-by: Armin Kuster <akuster808@gmail.com>
