RFR 8178794: krb5 client should ignore sname in incoming tickets

[Weijun Wang]

Hi Valerie

Please take a review of
   http://cr.openjdk.java.net/~weijun/8178794/webrev.00/

The sname field in the ticket is meant to be read by a server and the 
client should use the one inside KDC-REP's enc-part.

Thanks
Max