RFR(S/M): 7127708: G1: change task num types from int to uint in concurrent mark

[John Cuthbertson]

Hi Everyone,

Can I have another couple of volunteers review the changes for this CR - 
the webrev can be found at: 
http://cr.openjdk.java.net/~johnc/7127708/webrev.0/

Summary:
Exactly what it says the the CR's description:
> In G1's concurrent mark files we use an int for the task ID and call 
> it "task num". Recent work done by Jon Masamitsu:
>
> 7121618: Change type of number of GC workers to unsigned int
>
> has replaced int's with uint's for the worker IDs across our GCs. We 
> should also make the necessary changes in the G1 files to further 
> conform to that. While we're at it we should also rename "task num" as 
> "worker id" to be consistent with the rest of the GCs.


The changes were contributed by Kaushik Srenevasan from Twitter. I've 
looked them over and they look OK to me.

Testing: jtreg tests and specjvm (Kaushik); GC test suite with a low 
IHOP and marking verification (JohnC); a jprt test run is in the queue.

Thanks,

JohnC