hg: jdk/submit: 8215043: Remove declaration of parallel_worker_threads

[jcbeyler at google.com]

Changeset: 3ee633205603
Author:    manc
Date:      2018-12-09 19:18 -0800
URL:       http://hg.openjdk.java.net/jdk/submit/rev/3ee633205603

8215043: Remove declaration of parallel_worker_threads
Summary: Removing unused declaration
Reviewed-by: eosterlund, tschatzl

! src/hotspot/share/runtime/vm_version.hpp