hg: jdk-updates/jdk12u: 8217343: Shenandoah control thread should be able to run at critical priority

[shade at redhat.com]

Changeset: 52d604951e2e
Author:    shade
Date:      2019-01-19 11:20 +0100
URL:       http://hg.openjdk.java.net/jdk-updates/jdk12u/rev/52d604951e2e

8217343: Shenandoah control thread should be able to run at critical priority
Reviewed-by: rkennke

! src/hotspot/share/gc/shenandoah/shenandoahControlThread.cpp
! src/hotspot/share/gc/shenandoah/shenandoah_globals.hpp
+ test/hotspot/jtreg/gc/shenandoah/options/TestCriticalControlThreadPriority.java