[7u8] Request for approval for 7185471: Avoid Key Expansion when AES Cipher is re-init w/ the same key

[Deneau, Tom]

This is a request to backport the following changset into 7u8.  I believe Sean 
Coffey has agreed to sponsor this.

bugs.sun.com link: http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7185471

JDK8 changset: http://hg.openjdk.java.net/jdk8/tl/jdk/rev/9e97dacbfd35

-- Tom Deneau