Implemented get_authtok()/pam_get_authtok().

[prof79]

Hi!

For simple auth scenarios having to bother with a conversation function is overkill in my view.

Therefore I added (by copying from get_user()) one essential and missing PAM function, get_authtok() (referring to pam_get_authtok()) which is able to automatically prompt the user for a (non-echoed) authentication token or password.

As can be seen from the C side at https://web.archive.org/web/20190523222819/https://fedetask.com/write-linux-pam-module/#Authentication_function , pam_get_user() and pam_get_authtok() are sufficient to write succinct minimal auth libs.

For testing and demo I copied pam-sober to pam-sober-2 and modified it.

Btw the Linux package pamtester could be used as a replacement for test.c but of course you lost the flexibility of a custom PAM testing application.

Regards