RFR (S) 8232674: Fix build and rename ShenandoahBarrierSet::oop_load_from_native_barrier

[Aleksey Shipilev]

P1 bug:
  https://bugs.openjdk.java.net/browse/JDK-8232674

I believe this is caused by missing definition of this method:
  oop oop_load_from_native_barrier(oop obj, narrowOop* load_addr);

The way out is to generify it, the same way as we do it for SBS::load_reference_barrier. I also took
this opportunity to rename the method to match the other LRB flavor: now the
ShenandoahRuntime::load_reference_barrier_native wrapper looks right.

Fix:
  https://cr.openjdk.java.net/~shade/8232674/webrev.01/

Testing: Windows x86_64 build, Linux x86_64 build, hotspot_gc_shenandoah

-- 
Thanks,
-Aleksey