cryptnet: Sign-compare warning fix (try 2)

[Andrew Talbot]

Juan Lang wrote:

> Yes, I know what the value of CRYPT_E_NOT_FOUND is, and what the type
> of GetLastError is.  My point is, Microsoft confused signed and
> unsigned types for their last error values.  We have to live with it.
> 

Indeed. (And sorry, I didn't mean to sound patronizing.)

> I don't think the cost of adding silly casts or temporaries to avoid
> giving a warning on a common code idiom is worth it.

That's the trouble with some warnings: some instances you want to fix and
some you know you can safely ignore. I presumed that we were aiming to turn
this warning on permanently, but that may not be the intention, and maybe
the downside you highlight makes doing so not worthwhile.

-- 
Andy.