RFR: Disable complete bitmap verification in init mark

[Roman Kennke]

Am 27.06.2017 um 21:54 schrieb Aleksey Shipilev:
> Basically, our verifier spends >50% of time dealing with dead allocations now.
> It seems excessive to verify them before Init Mark, because it will rebuild the
> bitmaps anyway. After conc mark is done, it will blow most immediate garbage,
> and subsequent verification phases are good. Same reasoning applies to Full GC.
>
> Patch:
>   http://cr.openjdk.java.net/~shade/shenandoah/verifier-perf-new-allocs/webrev.01/
>
> Thanks,
> -Aleksey
>
Yes