ole32: fix offsets managment

[f.dorin at free.fr]

>Thank you for your first contribution, but first of all the subject
>isn't correct as the patch is to rpcrt4 instead of ole32. 
Oups, sorry. My apologies for this mistake. But I'm currently working on ole32 and I forgot this file belongs to rpcrt4. I will pay attention next time.

>Second of
>all, the patch is not correct as it is widl that is generating the
>wrong format string here:
>
>http://www.winehq.org/pipermail/wine-patches/2008-June/056332.html
>http://www.winehq.org/pipermail/wine-devel/2008-June/066587.html
Thanks for the links. I didn't think one moment it can be a widl bug. I believed it was a rpcrt4 one. 

François DORIN