d3d8/tests: make sure to use return values (LLVM/Clang)

[Henri Verbeet]

On 26 July 2011 10:57, Jacek Caban <jacek at codeweavers.com> wrote:
> It's better to test for the exact value in tests like hr == S_OK. It
> makes tests stricter.
I don't think that making tests more strict than necessary is a good
principle. (Not that it matters a lot here anyway, for most of these
D3D_OK is the only possible sucessful return value.)