RFR (M) 8183923: Get rid of FreeBlockDictionary and dithering

[Kim Barrett]

> On Jul 6, 2017, at 5:20 AM, Mikael Gerdin <mikael.gerdin at oracle.com> wrote:
> 
> Hi all,
> 
> Please review this cleanup inspired by looking at Roman's CMS cleanup :)
> 
> FreeBlockDictionary is an old abstraction for multiple CMS freelist datastructures which never appear to have been implemented, getting rid of it also simplifies some code in Metaspace so it's not all CMS stuff.
> 
> Testing: jprt
> Bug: https://bugs.openjdk.java.net/browse/JDK-8183923
> Webrev: http://cr.openjdk.java.net/~mgerdin/8183923/webrev.0/index.html
> 
> Thanks
> /Mikael

Looks good.