crypto/rand/rand_win.c: include "e_os.h" to get the default _WIN32_WINNT
crypto/rand/rand_win.c: include "e_os.h" to get the default _WIN32_WINNT

This helps decide if the BCrypt API should be used or not.

Fixes #8635

Reviewed-by: Matt Caswell <1fa2ef4755a9226cb9a0a4840bd89b158ac71391@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/8638)

openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl