RFR: 8229128: ZGC: Remove unused ZThreadRootsIterator

[Per Liden]

Thanks Erik!

/Per

On 8/5/19 1:51 PM, Erik Österlund wrote:
> Hi Per,
> 
> Looks good and trivial.
> 
> Thanks,
> /Erik
> 
> On 2019-08-05 13:37, Per Liden wrote:
>> ZThreadRootsIterator is no longer used and can be removed. Trivial?
>>
>> Bug: https://bugs.openjdk.java.net/browse/JDK-8229128
>> Webrev: http://cr.openjdk.java.net/~pliden/8229128/webrev.0
>>
>> /Per
>