RFR [8]: 2018-09-25, Bulk backports to sh/jdk8u

[Aleksey Shipilev]

http://cr.openjdk.java.net/~shade/shenandoah/backports/jdk8u-20181001/webrev.01/

This backports recent work to sh/jdk8u:

 [backport] Suppressing VSC++ warning locally
 [backport] Handle update_refs, class_unload, ref_proc in ShConcMark better
 [backport] Common liveness cache in ShHeap
 [backport] Inline/rename confusingly named methods in ShConcurrentMark
 [backport] Sort ShenandoahConcurrentMark methods/fields into logical groups
 [backport] Prepare tests for making UseShenandoahGC experimental
 [backport] Fix inconsistent "process weakrefs" logging
 [backport] Several AArch64 cleanups
 [backport] Trim down oop-equals verification
 [backport] Remove ShWB from formssel.cpp
 [backport] Use s-macro to keep GC phase enum and names in sync
 [backport] More AArch64 assembler cleanups
 [backport] Renaming ShenandoahParallelEvacuationTask to ShenandoahConcurrentEvacuationTask

Testing: hotspot_tier3_gc_shenandoah {fastdebug|release}, aarch64 build

Thanks,
-Aleksey