forward_pass/feature request

Very simply, it would be nice if there were a feature similar to forward_pass, but would forward the password unmodified. Example use case:

auth [success=2 default=ignore] pam_unix.so forward_pass
auth [success=1 default=ignore] pam_krb5.so try_first_pass

This allows unix or Kerberos login. Same config with pam_google_authenticator.so will not work, perhaps because it is expecting to strip a pin. (Eventually works, but first password prompt will always fail if you are trying krb5)

Thank you your work on this project.