Kerberos V4 changes to support "dual-headed" KDC

*  "dual-headed" KDC

	Changes provided to the Kerberos V4 Athena distribution
	allow the KDC to be "dual-headed".  Thus, the KDC will
	accept requests for user tickets via strong authenticated
	SPX global identities.

	The advantage is that users can provide a single password to
	obtain SPX and Kerberos credentials.  Users first obtain SPX
	credentials and using these credentials they authenticate to
	the KDC to obtain Kerberos credentials (TGT).  SPX and Kerberos
	can co-exist.  Since users don't need to know their Kerberos
	password, the KDC can be set with random keys for users.  This
	has two advantages.  If the KDC gets compromised, administrators
	don't need to give all their users new passwords.  Second,
	Kerberos users are protected from password guessing attacks.

	Another advantage is that Kerberos V4 can scale without
	requiring shared key relationships between realms.

*  Building new Kerberos V4 KDC and kinit program :

	-  Replace the following files in your Kerberos V4 kit

	-  Edit src/kuser/Makefile and src/server/Makefile
		The SPX_TOP variable should point to the top
		binary directory of your SPX distribution

	-  Build your kerberos V4 kit

*  Configuring your environment

	-  Create a principal called "krbtgt" in your local SPX domain
	   and register this principal with your CDC

	-  Install the "krbtgt" verifier credentials on the host where
	   the KDC is running (aka, KDC host)

	-  Edit a file on the KDC host called /kerberos/princ_trans

		This file contains mappings for global SPX names to
		local Kerberos principal name.  This file must NOT be
		writable by anyone but the adminstrator.  This file
		can be world readable.  Each line contains a global
		name (must be in double quotes if global name contains
		embedded spaces) followed by the Kerberos principal name.

		e.g.,   "/C=US/O=Digital/OU=LKG/CN=John R. User"  jruser

	-  Clients need SPX and Kerberos installed properly, configuration
	   files must be correct for both mechanisms.

		Add an entry in the /etc/cdc.conf file that maps the
		Kerberos realm name to the local SPX domain name


