winbase.h: Add a few casts

[Andrew Talbot]

Alexandre Julliard wrote:

> Andrew Talbot <Andrew.Talbot at talbotville.com> writes:
> 
>> Changelog:
>>     winelib: Add a few casts.
> 
> Why do you need them?
> 
Sorry. I confess that I was looking around with Splint, saw that the
difference between the returned types of some string functions differed
from their declared type, and thought - as these are library functions that
are used frequently - that it would be good to match them up with casts.

-- Andy.