Update library sites to use modern Java concurrency tools

[arthurp]

Many of the Orc library sites are implemented using Java monitors. Since those sites were implemented Java has added a number of concurrency tools to it's own library (such as ConcurrentLinkedQueue). We could get a significant performance gain by reimplementing Orc library sites based on new Java library classes and using lower level tools that already existed (such as AtomicInteger).

This issue tracks a number of small changes. They are grouped since they will not take much time and they are all closely related. I figured this would be less noisy.

Sites that should to be considered for reimplemention:

• Channel (could almost certainly be improved)
• Counter (could almost certainly be improved)
• Cell (can be eliminated entirely and implemented as an object)
• SyncChannel
• BoundedChannel
• Semaphore
• Ref

(This is basically the entire orc.lib.state package. But there may be other sites that could use a check. Anywhere that uses synchronized would be a good place to start.)

PS: This work may also get us close enough to removing all the old style Java sites that we could just kill them all and get ride of the shims.

[arthurp]

Before starting on this we should verify that the performance of the sites is actually important and is overwhelming the overhead.