Upstream merge to jdk-13+8

[Aleksey Shipilev]

On 2/14/19 9:07 PM, Roman Kennke wrote:
> Merged trivially. Testing hotspot_gc_shenandoah seems fine.
> 
> Changes:
> http://cr.openjdk.java.net/~rkennke/upstream-jdk13-merge-2019-02-14/changes.txt
> 
> In particular:
> - 8217874: Shenandoah: Clobbered register in
> ShenandoahBarrierSetAssembler::cmpxchg_oop()
> 
>  Ok to push?

Looks good to push.

-Aleksey