[11] RFR: Drop the workaround for JDK-8217717

[Aleksey Shipilev]

Back when we backported self-fixing barriers, we had to include the workaround for JDK-8217717 [1]:
  https://hg.openjdk.java.net/shenandoah/jdk11/rev/b16b63a399f3#l6.61

That workaround arrived through upstream 11.0.7 and no longer needed. Let's drop it:
  https://cr.openjdk.java.net/~shade/shenandoah/11u-drop-8217717/webrev.01/

It seems to be exactly the same method that is in BarrierSetC1::resolve_address. I checked
shenandoahBarrierSetC1.cpp is similar to what we have in jdk/jdk after this change.

Testing: hotspot_gc_shenandoah {fastdebug,release}

-- 
Thanks,
-Aleksey

[1] https://bugs.openjdk.java.net/browse/JDK-8217717