* kinit.c (krb5_validate_tgt): new function, takes a credential cache with an

* kinit.c (krb5_validate_tgt): new function, takes a credential cache with an
tgt with the "invalid flag" set, and asks the kdc to validate it. Wipes cache
and stores only the newly validated credential. (After all, there won't be any
others, because the invalid krbtgt couldn't have gotten them.) Most of the code
is taken from krb5_mk_req, since it did the right thing.
(main): add -v option, validates the ticket already in the selected cache.

git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@7894 dc483132-0cff-0310-8789-dd5450dbe970