RFR (XS) 8229176: Shenandoah should acquire CodeCache_lock without safepoint check

[Roman Kennke]

I needed to make this exact fix when backporting to shenandoah/jdk11.
Yes, is good. Thanks!

Roman


> P1 bug:
>   https://bugs.openjdk.java.net/browse/JDK-8229176
> 
> CodeCache_lock is defined with Monitor::_safepoint_check_never, should be acquired without safepoint
> check. New stronger assert introduced by JDK-8229000 fails because of that.
> 
> Fix:
> 
> diff -r 8f067351c370 src/hotspot/share/gc/shenandoah/shenandoahCodeRoots.cpp
> --- a/src/hotspot/share/gc/shenandoah/shenandoahCodeRoots.cpp   Mon Aug 05 16:27:30 2019 -0700
> +++ b/src/hotspot/share/gc/shenandoah/shenandoahCodeRoots.cpp   Tue Aug 06 11:08:36 2019 +0200
> @@ -201,5 +201,5 @@
>      }
>      case 2: {
> -      CodeCache_lock->lock();
> +      CodeCache_lock->lock_without_safepoint_check();
>        break;
>      }
> 
> Testing: hotspot_gc_shenandoah (massive failures before, no failures after)
>