RFR: Upstream merge to jdk-12+15

[Roman Kennke]

I should actually post list of changes:

http://cr.openjdk.java.net/~rkennke/upstream-jdk12-merge-2018-10-18/outgoing.txt

Roman

> Merge up to jdk-12+15 brings goodies:
> 
> - 8212054: Boilerplate to bind oopDesc::equals_raw() to actual raw
> implementation
> - 8212053: A few more missing object equals barriers
> - 8212074: Add method to peek the remaining tasks in task queues
> - 8211955: GC abstraction for LAB reserve
> - 8212178: Soft reference reclamation race in
> com.sun.xml.internal.stream.util.ThreadLocalBufferAllocator
> 
> Those are interesting for us too (conc-weakref, conc-coderoots,
> conc-classunloading):
> - 8210330: Make CLD claiming allow multiple claim bits
> - 8210498: nmethod entry barriers
> 
> I also included those two:
> - 8212616: x86_32 build failures after JDK-8210498 (nmethod entry barriers)
> - 8212617: ARM32 build failures after JDK-7041262 (VM_Version should be
> called instead of Abstract_VM_Version so that overriding works)
> 
> 
> Testing: tier3_gc_shenandoah
> 
> Ok?
> 
> Roman
>