RFR [8] 2018-12-05: Bulk backports to sh/jdk8

[Aleksey Shipilev]

http://cr.openjdk.java.net/~shade/shenandoah/backports/jdk8u-20181205/webrev.01/

This backports recent work to sh/jdk8u. Most of that stuff is redoing copyrights, renames, moves to
match what we did in sh/jdk for upstreaming.

Changes:

 [backport] Update copyrights
 [backport] Minor cleanup of Shenandoah SA
 [backport] Eliminating Shenandoah exposure to CLD
 [backport] Use ShenandoahAllocationThreshold in ShenandoahStaticHeuristics constructor
 [backport] Remove obsolete unused flags
 [backport] Remove ShenandoahWriteBarrierRB flag
 [backport] Rename VerifyObjectEquals to ShenandoahVerifyObjectEquals
 [backport] Clean up and regroup Shenandoah flags
 [backport] Shenandoah test groups should not include each other
 [backport] Fix various formattings and namings in shared GC code
 [backport] Shenandoah should @require Shenandoah, @key gc, and have good @test
 [backport] Fix indentation of CriticalNative* tests
 [backport] Disable heap iteration for Shenandoah in SA
 [backport] remove useless change in loopnode.cpp
 [backport] Reformat Shenandoah tests
 [backport] Remove obsolete and ignored TestHeapAlloc
 [backport] Move Shenandoah tests to proper locations
 [backport] Drop Shenandoah from test names
 [backport] Prefix Shenandoah tests with "Test"
 [backport] Rename UINT64_FORMAT_HEX_W to UINT64_FORMAT_X_W
 [backport] Move ShenandoahGCTracer to gc/shenandoah
 [backport] Rename fields in (SA) ShenandoahHeap.java to omit 'Regions' and 'Field' suffix
 [backport] Trim unused code from Shenandoah SA
 [backport] Separate "passive" heuristics from "adaptive"
 [backport] Fail early when critical barriers are disabled
 [backport] Some Shenandoah related additions to SA
 [backport] Print number of threads in Shenandoah SA heap summary
 [backport] Re-label Shenandoah GC causes (SA&GC)

Testing: hotspot_gc_shenandoah {fastdebug|release}

Thanks,
-Aleksey