Additional CVE-2014-0224 protection.

Return a fatal error if an attempt is made to use a zero length
master secret.
(cherry picked from commit 006cd7083f76ed5cb0d9a914857e9231ef1bc317)

ssl/s3_pkt.c

@@ -1727,7 +1727,7 @@ int ssl3_do_change_cipher_spec(SSL *s)
 
 	if (s->s3->tmp.key_block == NULL)
 		{
-		if (s->session == NULL) 
+		if (s->session == NULL || s->session->master_key_length == 0)
 			{
 			/* might happen if dtls1_read_bytes() calls this */
 			SSLerr(SSL_F_SSL3_DO_CHANGE_CIPHER_SPEC,SSL_R_CCS_RECEIVED_EARLY);