6965072: update SDP support

[Michael McMahon]

Alan Bateman wrote:
>
> Michael - do you mind reviewing this one?
>
> This is a change to the SDP support to make it easy to provide an API 
> in the future.  For now it includes a simple implementation specific 
> API. The existing transparent support continues to work but is 
> reorganized to allow for both transparent and API usage. The webrev 
> with the changes is here:
>   http://cr.openjdk.java.net/~alanb/6965072/webrev/
>
> Thanks,
> Alan.
>
>
Looks fine to me.

- Michael.