Request for review - 7131629

[Jon Masamitsu]

This is a set of changes to CMS GC code to templatize some
classes so that they can be used more generally.  The additional
usages will be to create free lists of items other than the
CMS FreeChunk's.   The templatized classes are moved to
the shared/vm/memory/ directory.

7131629: Generalize the CMS free list code

http://cr.openjdk.java.net/~jmasa/7131629/webrev.00/

Thanks.