[sh/jdk8u] Backport region count/region size fixes

[Zhengyu Gu]

I would like to backport following two CRs that fix region count/region 
size calculations.

8265239: Shenandoah: Shenandoah heap region count could be off by 1
8266802: Shenandoah: Round up region size to page size unconditionally

Both patch do not apply cleanly.

8265239:
   - Extra include "utilities/align.hpp"
   - Manually resolved minor merge conflict.

8266802:
   - Fixed new assertion. Cannot format assertion message in 8u.
   - Removed "@requires vm.gc.Shenandoah" annotation in new test, 8u does
     not recognize the annotation.


Test:
   hotspot_gc_shenandoah, including new test.

Thanks,

-Zhengyu