RFR (XS) 8242267: Shenandoah: regions space needs to be aligned by os::vm_allocation_granularity()

[Roman Kennke]

Looks good.

Roman

> Bug:
>   https://bugs.openjdk.java.net/browse/JDK-8242267
> 
> SAP folks report their Windows CI fails Shenandoah tests.
> 
> I believe this is the fix:
> 
> diff -r 3f8d03880bf5 src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp
> --- a/src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp        Tue Apr 07 03:25:11 2020 +0000
> +++ b/src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp        Tue Apr 07 11:48:56 2020 +0200
> @@ -284,4 +284,5 @@
>    size_t region_align = align_up(sizeof(ShenandoahHeapRegion), SHENANDOAH_CACHE_LINE_SIZE);
>    size_t region_storage_size = align_up(region_align * _num_regions, region_page_size);
> +  region_storage_size = align_up(region_storage_size, os::vm_allocation_granularity());
> 
>    ReservedSpace region_storage(region_storage_size, region_page_size);
> 
> Testing: Linux x86_64 hotspot_gc_shenandoah + asked SAP folks to confirm
>