Fix null-pointer assignment in do_change_cipher_spec() revealed

by using the Codenomicon TLS Test Tool (CAN-2004-0079)
Fix flaw in SSL/TLS handshaking when using Kerberos ciphersuites
(CAN-2004-0112)
Ready for 0.9.7d build

Submitted by: Steven Henson
Reviewed by: Joe Orton
Approved by: Mark Cox