miri: WinApi SYSTEM_INFO `dwPageSize` always returning 0

This is a rather weird issue I reported first in the page_size crate. When running Miri with any of the Tier 1 Windows targets the crate reports page size 0, which is a fatal error for my use, where I want to allocate aligned to the page boundary.

This is witnessed most easily by the GitHub Action run. My code panics when the page size is not a power of two, so in this case it crashes with:

thread 'main' panicked at 'detected page size 0 that is not a power of two, this is unsupported', src/alignment.rs:111:21

The page size query works perfectly well for Unix targets.

Replication

This can be confirmed by referencing page_size and asking for it like this:

fn main() {
    println!("Page size: {}", page_size::get());
}

and running Miri:

cargo +nightly miri run --target x86_64-pc-windows-gnu

resulting in:

> Page size: 0

Whereas running it without Miri gives the correct result (on my PC it’s 4KB):

cargo run

> Page size: 4096

If it matters, the host OS seems to not affect this, the issue is the same running the command both from Unix and Windows.