stacker::grow Causes Invalid Memory Access

The stucker::grow function appears to cause invalid memory access when the input stack_size is not divisible by the page size. This issue likely originates from a miscalculation in the following code snippet:

let page_size = page_size();
let requested_pages = stack_size
    .checked_add(page_size - 1)
    .expect("unreasonably large stack requested") / page_size;
let stack_pages = std::cmp::max(1, requested_pages) + 2;
let stack_bytes = stack_pages.checked_mul(page_size);

I have tested my code extensively with various stack_size values and observed that this issue occurs specifically when the input stack_size is not divisible by the page size.

Start at the stacker::grow function and inspect the page-count and stack-byte calculations shown in the issue. Reproduce the invalid memory access with stack_size values that are not divisible by the page size. Done means those inputs no longer cause invalid memory access and the behavior is covered by a regression test.