pam_winbind: fix warn_pwd_expire implementation.

pam_winbind: fix warn_pwd_expire implementation.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=9056

warn_pwd_expire parameter is not working as documented in pam_winbind manual
page. This patch adds missing bit and allows disabling warning message fully,
i.e. setting warn time to zero days.

Guenther

Signed-off-by: Guenther Deschner <gd@samba.org>
Reviewed-by: Andreas Schneider <asn@samba.org>
Reviewed-by: Guenther Deschner <gd@samba.org>
Autobuild-User(master): Günther Deschner <gd@samba.org>
Autobuild-Date(master): Wed Dec  3 21:36:49 CET 2014 on sn-devel-104