oleaut32: Fix failing VarMod tests in WinXP, fix VarMod(VT_DECIMAL) in Wine

[Robert Shearman]

a_villacis at palosanto.com wrote:
> In a preparation for a possible implementation of IDispatch
> tests in oleaut32, I decided to clean up the failing tests in
> Windows XP:
>   

Great, thanks for fixing this.

I was about to do this myself. It's about time we get the number of 
failing tests on XP as close to zero as possible.

-- 
Rob Shearman