r20687: Implement grace logons for offline authentications in pam_winbind.

r20687: Implement grace logons for offline authentications in pam_winbind.

In case a user authenticated sucessfully and his password just expired
while beeing disconnected, we should allow a user to logon (given a
clear warning). We currently forced the user into a password change
dialogue in that scenario; this did not make much sense while offline.

Guenther
(This used to be commit 668b278653acfc4de7807834988f7af557e608a5)