Heimdal at least up through 1.2 incorrectly encrypts the TGS response
in the session key not the subkey when a subkey is supplied. See RFC
4120 page 35. Work around this by trying decryption using the session
key after the subkey fails.
* decode_kdc_rep.c: rename to krb5int_decode_tgs_rep; only used for
TGS and now needs to take keyusage
* gc_via_tkt: pass in session key and appropriate usage if subkey
Note that the dead code to process AS responses in decode_kdc_rep is
not removed by this commit. That will be removed as FAST TGS client
support is integrated post 1.7.
Commit By: hartmans