ntdll: Fix add_access_ace

[Mike McCormack]

Hi James,

James Hawkins wrote:

> These changes make the advapi32 tests pass as well.
> 
> Changelog
> * Fix calculation of generic pointers.
> * Minor cleanups.

Thanks for the fixes.  This makes Office 2003 work again for me.

>      if ((DWORD)(pAceHeader + dwAceSize) > (DWORD)(pAcl + pAcl->AclSize))
>          return STATUS_ALLOTTED_SPACE_EXCEEDED;

I think you might have missed one here.  The above pointer arithmetic 
seems like it will make the wrong calculation.  Maybe something like the 
following would work better:

   if ( &((char*)pAceHeader)[dwAceSize] > &((char*)pAcl)[pAcl->AclSize] )

Mike