Bugfix with std::mem (modern Rust)

[therustmonk]

Can't compile in windows without std::mem import.

stack_protected.rs

#[cfg(windows)]
fn page_size() -> usize {
    unsafe {
        let mut info = mem::zeroed(); // this fails
        libc::GetSystemInfo(&mut info);
        info.dwPageSize as usize
    }
}

[zonyitoo]

Hmm, I should just merge the fix on context-rs.