[security-dev 01357]: 6894643: Separate out dependency on Kerberos

[Vincent Ryan]

Hello all,

I'm proposing a further change that enables JSSE to work when Kerberos is not
present at runtime:

  http://cr.openjdk.java.net/~vinnie/6894643/webrev.00/

(This continues the removal of static dependencies begun in CR 6885204.)

Please comment.
Thanks.