Code review request 8023230, The impl of KerberosClientKeyExchange maybe not exist

[Xuelei Fan]

Hi Weijun,

Please review this update when you are available.

webrev: http://cr.openjdk.java.net/~xuelei/8023230/webrev.00/

If package sun.security.ssl.krb5 does not exist, the impl of
KerberosClientKeyExchange (krb5.KerberosClientKeyExchangeImpl) will not
present as well. Need to consider this case in the implementation of
sun.security.ssl.KerberosClientKeyExchange.

Thanks,
Xuelei