shlwapi: Correct AssocCreate and tests

[Jacek Caban]

Hi Alistair,

Alistair Leslie-Hughes wrote:
> Hi,
>    The spec file specified 4 parameters but it only takes 3.
>    Validate parameters to XP.
>    Added test cases.
>
>    Tested on win98 and XP.
>
> Changelog:
>     shlwapi: Correct AssocCreate and tests
>

+    hr = pAssocCreate(IID_NULL, &IID_NULL, NULL);
+    ok(hr == E_INVALIDARG, "Unexpected result : %08x\n", hr);


refiid arguments looks like an interface id (and the whole function 
looks similar to IClassFactory::CreateInstance), so it would be 
interesting to add test of IID_IUnknown.


Jacek