RFR: Simplify parallel synchronizer roots iterator

[Aleksey Shipilev]

On 05/10/2017 04:11 PM, Roman Kennke wrote:
> http://cr.openjdk.java.net/~rkennke/simplify-sync-roots/webrev.01/

The idea sounds fine.

 *) my_cur and next_block variables could be *void, to avoid clutter?

 *) I still see the asserts that reference CLAIMEDMARKER -- does it even build
with fastdebug?

Thanks,
-Aleksey