CryptGenRandom expects DWORD

[dsprenkels]

Upstream copy of PQClean/PQClean#438

[dsprenkels]

This is probably as easy as directly applying https://github.com/PQClean/PQClean/commit/45c8d1e073367cb4b991a1d690dbdcd8bbf4ed46.diff

[thomwiggers]

Maybe you want to actually do some error handling; the cast I added might truncate.

[thomwiggers]

Fixed by #40