RRFR 8002356: Add ForkJoin common pool and CountedCompleted

[Chris Hegarty]

I would like to re-start [1] review discussion of the changes to 
ForkJoinXXX ( add a default common pool, task tags, and implementation 
updates ), and the addition of CountedCompleter, as part of part of JEP 
155 [2].

These changes are of course coming form Doug and the JSR 166 EG members. 
I have done a quick sanity review, and the changes reflect what is in 
Doug's CVS. I need to spend more time reviewing myself, others on the 
list have more experience with these new API already and may have 
valuable feedback.

specdiff:
 
http://cr.openjdk.java.net/~chegar/8002356/ver.00/specdiff/java/util/concurrent/package-summary.html

webrev:
   http://cr.openjdk.java.net/~chegar/8002356/ver.00/webrev/webrev/

-Chris.

[1] http://openjdk.java.net/jeps/155
[2] 
http://mail.openjdk.java.net/pipermail/core-libs-dev/2012-November/012153.html