RFR: Remaining Shenandoah backports jdk/jdk -> sh/jdk11

[Roman Kennke]

>> This backports the following changes to sh/jdk11:
>>
>> JDK-8221751: Shenandoah: Improve SATB enqueueing
>> JDK-8221848: Shenandoah: ArrayCopy post-barrier improvements
>> JDK-8222227: Shenandoah: Fix Traversal GC weak roots handling in
>> final-traversal pause
>> JDK-8222259: Shenandoah: Pre-evacuate string-dedup roots in Traversal GC
>> JDK-8222188: Shenandoah: Adjust Shenandoah work gang types
>> JDK-8218468: Load barrier slow path node should be MachTypeNode
>> JDK-8223651: Build fails with --with-jvm-features=-jfr and
>> --disable-precompiled-headers
>>
>> Changes transplanted with minimal and simple changes.
>> Testing: hotspot_gc_shenandoah fine
>>
>> Ok?
> 
> Okay. Is there a webrev that shows the changes, for the record?

Oops, forgot to include it:

http://cr.openjdk.java.net/~rkennke/backport-jdk11-2019-05-16/webrev.00/

Roman