Deprecate and remove OPIE from PAM.

Deprecate and remove OPIE from PAM.

This will require user intervention to manually disable OPIE usage or
cleanly reinstall pam.d/* (even better if no modifications were done).
Due to very strict used "requisite" requirements any pam_opie loading
error will result in unusable system except for singe user mode.
Add warning for the user. Sooner or later this will need to be done.

While there, disable installing /etc/pam.d/rsh script. It can be removed.