RFR: Allocation failure injection machinery

[Roman Kennke]

Am 19.01.2018 um 18:05 schrieb Aleksey Shipilev:
> http://cr.openjdk.java.net/~shade/shenandoah/inject-alloc-failure/webrev.01/
> 
> Found many bugs in Degenerated GC with this machinery. But it is separate from the rest of the code,
> and is useful to have for general testing: for example, to test if baseline without Degenerated GC
> fails the same way. Therefore, this patch splits the machinery out.
> 
> Testing: hotspot_gc_shenandoah
> 
> Thanks,
> -Aleksey
> 

Looks good.