RFR: Full GC should not always update references

[Roman Kennke]

Am 05.07.2018 um 20:16 schrieb Aleksey Shipilev:
> http://cr.openjdk.java.net/~shade/shenandoah/fullgc-no-ur/webrev.01/
> 
> This resolves one of the TODOs, and makes Full GC faster because of that. We are sure this is
> correct, because asserts in phase1 would detect unexpectedly forwarded objects. New Verifier code
> would also assert has_forwarded bits are correctly (re)set.
> 
> Testing: tier3_gc_shenandoah, benchmarks with "passive"

Very good, thank you!
Roman