hg: jdk/sandbox: 8229000: Fix lock and reenable assert in Monitor::check_safepoint_state

[chris.hegarty at oracle.com]

Changeset: c38cca5ffb66
Author:    coleenp
Date:      2019-08-05 11:16 -0400
URL:       https://hg.openjdk.java.net/jdk/sandbox/rev/c38cca5ffb66

8229000: Fix lock and reenable assert in Monitor::check_safepoint_state
Reviewed-by: dholmes, kbarrett

! src/hotspot/share/gc/cms/concurrentMarkSweepGeneration.cpp
! src/hotspot/share/runtime/mutex.cpp