comctl32/tests: Better deal with the unsupported CreateWindowExW() case.

[Nikolay Sivov]

On 12/1/2013 19:24, Francois Gouget wrote:
> No matter why CreateWindowExW() fails, if we don't have an hwnd we have
> to skip the tests.
> ---
>
It doesn't look like we have to use *Ex version at all.