This allocator now supports alignments greater than page size, with the
same implementation as it used before.

This is a partial revert of ceb0a632cfd6a4eada6bd27bf6a3754e95dcac86.

It looks like VirtualAlloc2 has better solutions to this problem,
including features such as MEM_RESERVE_PLACEHOLDER and MEM_LARGE_PAGES.
This possibility can be investigated as a follow-up task.