[1/2][try 3] ddraw/tests: add test for rendering vertices with zero rhw

[H. Verbeet]

On 07/01/2008, Alexander Dorofeyev <alexd4 at inbox.lv> wrote:
> Hi.
>
> I couldn't reproduce any problems with this patch on wine or on windows, but I
> moved coordinates of retrieved pixel a bit away from edges. I hope this was the
> problem :-/
>
It could've been a depth buffer issue as well. I'm not exactly sure
what the state of the depth buffer is when the test is run, but in
general it appears the GF8 rounds slightly different compared to
previous nvidia cards.