RFR: Reinstate single-threaded reference processing

[Aleksey Shipilev]

On 10/16/2018 06:10 PM, Roman Kennke wrote:
> Diff:
> http://cr.openjdk.java.net/~rkennke/redo-1thread-refproc/webrev.01.diff/
> Full:
> http://cr.openjdk.java.net/~rkennke/redo-1thread-refproc/webrev.01/

OK!

-Aleksey