Resync java.util.concurrent classes with Dougs CVS - Sep 2013

The concurrency classes, java.util.concurrent, are mainly written and maintained by Doug Lea, with assistance from members of JCP JSR-166 Expert Group. As such they have been improving the implementation, fixing bugs, and making spec clarifications in their own CVS repository. This is the master copy of these source files.

This issue proposes to sync the OpenJDK version of these source files with the source that is in Dougs CVS.