RFR: Unclutter ShenandoahHeap, take 3

[Aleksey Shipilev]

http://cr.openjdk.java.net/~shade/shenandoah/unclutter-sh-heap-3/webrev.01/

This is hopefully final bunch of touchups to ShenandoahHeap for a while. Patch train includes:

 *) Remove unused ShenandoahEvacuateRootsClosure
 *) Rename ShHeap::shenandoahPolicy -> ShHeap::shenandoah_policy
 *) Handle ShHeap::time_since_last_millis for RMI users
 *) Inline ShHeap::monitoring_support into header

Testing: tier1_gc_shenandoah {fastdebug|release}, tier3_gc_shenandoah (running)

Thanks,
-Aleksey