Makefile.in: Added flags to turn on the encryption option

Makefile.in: Added flags to turn on the encryption option

authenc.c (telnet_spin): Implemented the telnet spin function, which
	works by calling the Scheduler with the tty_lockout flag set.

main.c (main): If the -x option is given, set the autologin,
	wantencryption, and auth_enable_encrypt flag.  They enable
	authentication, enforcement of the encryption option, and a flag to
	the auth layer to negotiate authentication with mandatory encryption
	option.

telnet.c (telnet): If the wantencryption flag is set (because the user
	has given the -x option, then we enforce that encryption must be
	turned on.  The user will not be able to type to the network stream
	until encryption is enabled, and if encryption is refused, the client
	will print an error message.
	(Scheduler): If the tty_lockout flag is set, then don't process
	keyboard read events.  This prevents the user from typing over the
	network until encryption is enabled.

utilities.c (printsub): Added print support for the authentication
	must-encrypt option.

git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@7662 dc483132-0cff-0310-8789-dd5450dbe970