The recommendation for windows is hopelessly out of date. On Vista and up CryptGenRandom is exported directly from Advapi32. That said... just use the CNG functions (BCryptGenRandom[1]), which is what both RtlGenRandom and CryptGenRandom use under the covers. BCrypt.dll is going to get loaded either way.
[1] https://msdn.microsoft.com/en-us/library/windows/desktop/aa3...