RFR: Refactor allocation seqnum handling: split mutator/GC allocs, merge with other metadata handling

[Zhengyu Gu]

Good to me.

-Zhengyu

On 02/20/2018 01:06 PM, Roman Kennke wrote:
> Looks good to me.
> 
> On Tue, Feb 20, 2018 at 6:59 PM, Aleksey Shipilev <shade at redhat.com> wrote:
>> http://cr.openjdk.java.net/~shade/shenandoah/alloc-seqnums/webrev.01/
>>
>> This refactors allocation seqnum machinery, so that we have more data to feed the heuristics with.
>> Notably, this should help Roman's work on Traversal GC that wants to ignore some of the newly
>> allocated regions.
>>
>> Testing: hotspot_gc_shenandoah {fastdebug|release}
>>
>> Thanks,
>> -Aleksey
>>