hg: jdk/sandbox: 8230126: delay_to_keep_mmu can delay shutdown

[chris.hegarty at oracle.com]

Changeset: d1a6f72e4aec
Author:    kbarrett
Date:      2019-08-28 14:06 -0400
URL:       https://hg.openjdk.java.net/jdk/sandbox/rev/d1a6f72e4aec

8230126: delay_to_keep_mmu can delay shutdown
Summary: Wait on CGC_lock instead of sleeping to provide the delay.
Reviewed-by: sangheki, sjohanss

! src/hotspot/share/gc/g1/g1ConcurrentMarkThread.cpp
! src/hotspot/share/gc/g1/g1ConcurrentMarkThread.hpp