hg: jdk/sandbox: 8240902: JDI shared memory connector can use already closed Handles

[chris.hegarty at oracle.com]

Changeset: 0c03ed579379
Author:    pchilanomate
Date:      2020-03-20 00:32 +0000
URL:       https://hg.openjdk.java.net/jdk/sandbox/rev/0c03ed579379

8240902: JDI shared memory connector can use already closed Handles
Summary: Add refcount to keep track of connection access
Reviewed-by: dholmes, dcubed, sspitsyn

! src/jdk.jdi/share/native/libdt_shmem/shmemBase.c