RFR [8]: 2018-10-18, Bulk backports to sh/jdk8

[Aleksey Shipilev]

http://cr.openjdk.java.net/~shade/shenandoah/backports/jdk8u-20181018/webrev.01/

There were many unclean applies and specific whitespace changes, please take a careful look.

Changes include:

 [backport] Partial infrastructure for suspendible workers
 [backport] Fix up superfluous changes against upstream
 [backport] Readjust ShenandoahStrDedupStress test to avoid timeout
 [backport] Assert that Shenandoah does not trip JDK-8211926
 [backport] Added a few missed worker sessions for worker tasks
 [backport] Remove unused SA ShenandoahHeapRegionSet.java
 [backport] Add JFR parallel and concurrent events (infrastructure)
 [backport] Remove ShenandoahCompileCheck
 [backport] Clean up Shenandoah configurations in shared tests
 [backport] A few more missing object equals barriers
 [backport] c2 verification pass fixes for CAS
 [backport] Move HdrSeq and BinaryMagnitudeSeq into Shenandoah utilities
 [backport] Enable NUMA by default
 [backport] Force termination logic is inverted
 [backport] Need to step over GC barriers in Node::eqv_uncast()
 [backport] Fixed ShenandoahStrDedupStress test that causes negative index OOB exception

Testing: hotspot_tier3_gc_shenandoah {fastdebug|release}

Thanks,
-Aleksey