Changes to the Kerberos SSL code by Jeffrey Altman <jaltman@columbia.edu>

His comments are:

 . adds use of replay cache to protect against replay attacks

 . adds functions kssl_tgt_is_available() and
   kssl_keytab_is_available() which are used within s3_lib.c
   and ssl_lib.c to determine at runtime whether or not
   KRB5 ciphers can be supported during the current session.