[7u4] Request for approval for 7109837: Provide a mechanism for computing an Adler32 checksum for the contents of a ByteBuffer

[Xueming Shen]

This is a request to backport a JDK8 fix into JDK 7u4

7109837: Provide a mechanism for computing an Adler32 checksum for the 
contents of a ByteBuf
http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7109837

The JDK 8 changeset is at

http://cr.openjdk.java.net/~sherman/7109837/webrev

The proposed change for jdk7u4 is "slightly" different, the webrev for 
public repository is

http://cr.openjdk.java.net/~sherman/7109837_7u4/webrev

in which we added the mechanism that can be accessed via 
sun/misc/SharedSecrets

Thanks,
Sherman