RFR 8224875: Shenandoah: ParallelCleaning code unloading should take lock to protect shared code roots array

[Zhengyu Gu]

> 
>    assert_locked_or_safepoint(CodeCache_lock);
>    ShenandoahSpinLocker locker(CodeCache_lock->owned_by_self() ? NULL : &_recorded_nms_lock);

Okay. http://cr.openjdk.java.net/~zgu/JDK-8224875/webrev.03/

-Zhengyu

> 
> 
> Thanks,
> -Aleksey
>