RFR [sh/8u]: Backport elimination of forwarding pointer

[Roman Kennke]

> On 10/28/19 6:06 PM, Roman Kennke wrote:
>> Ha, and it missed the webrev link:
>> http://cr.openjdk.java.net/~rkennke/nofwdptr-sh8/webrev.00/
> 
> More thorough review:
> 
> *) shenandoahBarrierSetAssembler_x86.cpp, SBSA::load_reference_barrier_not_null, why EVACUATION was
> dropped here?
> 
>   91   __ testb(gc_state, ShenandoahHeap::HAS_FORWARDED);
> 

In order to match jdk11:

https://hg.openjdk.java.net/shenandoah/jdk11/rev/77ca9dd0bf0a#l3.61

Also, EVACUATION is a subset of HAS_FORWARDED, right?

Roman