[8] RFR: Fix leftover commented out code in ShenandoahRuntime::load_reference_barrier_JRT

[Roman Kennke]

Oh, oops. Yes, please do that.

Roman

> Another problem in sh/jdk8, leftover commented code that is supposed to be a production code.
> 
> diff -r e1961573bf06 src/share/vm/gc_implementation/shenandoah/shenandoahRuntime.cpp
> --- a/src/share/vm/gc_implementation/shenandoah/shenandoahRuntime.cpp   Wed Oct 23 20:57:10 2019 +0200
> +++ b/src/share/vm/gc_implementation/shenandoah/shenandoahRuntime.cpp   Wed Oct 23 21:16:34 2019 +0200
> @@ -58,8 +58,6 @@
> 
>  JRT_LEAF(oopDesc*, ShenandoahRuntime::load_reference_barrier_JRT(oopDesc* src))
> -  oop result = ShenandoahBarrierSet::barrier_set()->load_reference_barrier(oop(src));
> +  oop result = ShenandoahBarrierSet::barrier_set()->load_reference_barrier_mutator(oop(src));
>    return (oopDesc*) result;
> -//  oop result = ShenandoahBarrierSet::barrier_set()->load_reference_barrier_mutator(oop(src));
> -//  return (oopDesc*) result;
>  JRT_END
> 
> Testing: hotspot_gc_shenandoah
>