Support challenge-response files outside user's home directory.
Support challenge-response files outside user's home directory.

Having the challege-response data inside the home directory won't
work very well if the YubiKey is to unlock an ecryptfs encrypted
home directory.

Yubico/yubico-pam,Yubico/yubico-pam,eworm-de/yubico-pam,Yubico/yubico-pam,eworm-de/yubico-pam,madrat-/yubico-pam,eworm-de/yubico-pam,madrat-/yubico-pam,madrat-/yubico-pam