git: openjdk/loom: fibers: Added jni monitor vthread test.

[duke]

Changeset: bd77078c
Author:    lmesnik <leonid.mesnik at oracle.com>
Date:      2021-09-09 18:30:00 +0000
URL:       https://git.openjdk.java.net/loom/commit/bd77078c2dd3ad1640419a585f4d629981ef59dc

Added jni monitor vthread test.

+ test/hotspot/jtreg/runtime/vthread/JNIMonitor/JNIMonitor.java
+ test/hotspot/jtreg/runtime/vthread/JNIMonitor/libJNIMonitor.cpp