hg: jdk/sandbox: 8237586: Shenandoah: provide option to disable periodic GC

[chris.hegarty at oracle.com]

Changeset: 7c606c26d02a
Author:    shade
Date:      2020-01-21 20:58 +0100
URL:       https://hg.openjdk.java.net/jdk/sandbox/rev/7c606c26d02a

8237586: Shenandoah: provide option to disable periodic GC
Reviewed-by: zgu

! src/hotspot/share/gc/shenandoah/shenandoahHeuristics.cpp
! src/hotspot/share/gc/shenandoah/shenandoah_globals.hpp
! test/hotspot/jtreg/gc/shenandoah/TestPeriodicGC.java