hg: jdk/sandbox: implement version downgrad protection

[xuelei.fan at oracle.com]

Changeset: 1fc6a8df1958
Author:    xuelei
Date:      2018-05-26 15:15 -0700
URL:       http://hg.openjdk.java.net/jdk/sandbox/rev/1fc6a8df1958

implement version downgrad protection

! src/java.base/share/classes/sun/security/ssl/DHKeyExchange.java
! src/java.base/share/classes/sun/security/ssl/RandomCookie.java
! src/java.base/share/classes/sun/security/ssl/ServerHello.java