hg: jdk/jdk15: 8246381: VM crashes with "Current BasicObjectLock* below than low_mark"

[jamsheed.c.m at oracle.com]

Changeset: f8cffefd6e9b
Author:    jcm
Date:      2020-07-16 08:28 -0700
URL:       https://hg.openjdk.java.net/jdk/jdk15/rev/f8cffefd6e9b

8246381: VM crashes with "Current BasicObjectLock* below than low_mark"
Summary: save and restores "donotunlock" flag in check_and_handle_async_exceptions
Reviewed-by: coleenp, dholmes

! src/hotspot/share/interpreter/interpreterRuntime.cpp
! src/hotspot/share/runtime/thread.cpp
! src/hotspot/share/runtime/thread.hpp