[11] RFR: Clean up Shenandoah GC epilogue

[Roman Kennke]

Ok!

Thanks,
Roman

> Recent sh/jdk11 backports added JvmtiExport::gc_epilogue to ShenandoahMarkCompact twice. Funnily,
> there is no such call in other Shenandoah code, and that is not catastrophic, because that call is
> not even needed starting the very early JDK 8 (see JDK-8225437). So, I would like to remove it. It
> is already gone in jdk/jdk, so this is 11-shenandoah fix.
> 
> While we are at it, move CodeCache::gc_epilogue into the same epilogue block. That call is also gone
> in jdk/jdk, so this is again 11-shenandoah fix.
> 
> We would do the same for sh/jdk8, after LRB/nofwdptr gets there.
> 
> Fix:
> 
> diff -r 784ce5186930 src/hotspot/share/gc/shenandoah/shenandoahMarkCompact.cpp
> --- a/src/hotspot/share/gc/shenandoah/shenandoahMarkCompact.cpp Mon Aug 12 12:07:29 2019 +0200
> +++ b/src/hotspot/share/gc/shenandoah/shenandoahMarkCompact.cpp Mon Aug 12 21:14:06 2019 +0200
> @@ -174,11 +174,11 @@
>      SharedRestorePreservedMarksTaskExecutor exec(heap->workers());
>      _preserved_marks->restore(&exec);
>      BiasedLocking::restore_marks();
>      _preserved_marks->reclaim();
> 
> -    JvmtiExport::gc_epilogue();
> +    CodeCache::gc_epilogue();
>    }
> 
>    // Resize metaspace
>    MetaspaceGC::compute_new_size();
> 
> @@ -186,13 +186,10 @@
>    for (uint i = 0; i < heap->max_workers(); i++) {
>      delete worker_slices[i];
>    }
>    FREE_C_HEAP_ARRAY(ShenandoahHeapRegionSet*, worker_slices);
> 
> -  CodeCache::gc_epilogue();
> -  JvmtiExport::gc_epilogue();
> -
>    heap->set_full_gc_move_in_progress(false);
>    heap->set_full_gc_in_progress(false);
> 
>    if (ShenandoahVerify) {
>      heap->verifier()->verify_after_fullgc();
> 
> Testing: hotspot_gc_shenandoah
>