'int' is enough for 'length' to migrate code from x86 to x64

[FrankLike via Digitalmars-d]

> That I partially, fractionally even, agree with. We agonized 
> for a long time about what to do to improve on the state of the 
> art back in 2007 - literally months I recall. Part of the 
> conclusion was that reverting to int for object lengths would 
> be a net negative.
>
> Andrei

All of these discussions, let me known how to do about 'length',D 
better than c,it's a system language.

For WindowsAPI: cast(something)length ,and other modify it to 
size_t.

Thank you all.