Description of enhancement:
Everything is restricted on local physical access only:

If user 'foo' is already logged on local console it should not be required to
enter the password to login for 'foo' on another local console - the original
console is alrady accessible for any fraud anyway.

Leaving console with any user running "exec top s" will be no longer safe with
this feature in effect - it should NEVER be default!


Steps for The Show:
1. /etc/pam.d/system-auth line before pam_unix.so:
    auth sufficient /lib/security/$ISA/pam_console.so johanka
2. Login on local console as user 'foo' - enter password.
3. Login on local console as user 'foo' - no password required.
4. Login on local console as user 'bar' - enter password.