- krb5_parse_name now allows zero-length realms

- krb5_parse_name now allows zero-length realms
- krb5_get_fallback_host_realm made string-safe
  (now takes *krb5_data instead of a maybe-string)
- conditionalized some previously-missed bits of debugging output
  (some of this should probably get nuked entirely since it's
  not really interesting anymore, but keeping easy debugging
  hooks for the core referral logic seems very useful)
- return first-hop referral TGT for ccache
  (but should maybe not do so if already cached?)
- fixed a couple of stupid bugs in fallback realm code
- cleaned up some memory leaks (more surely remain)
- state updated

git-svn-id: svn://anonsvn.mit.edu/krb5/branches/referrals@18573 dc483132-0cff-0310-8789-dd5450dbe970