RFR: 8229128: ZGC: Remove unused ZThreadRootsIterator

[Per Liden]

Thanks Stefan!

/Per

On 8/5/19 4:03 PM, Stefan Karlsson wrote:
> Looks good.
> 
> StefanK
> 
> 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