WINED3D: Fix a possible null dereference.

[H. Verbeet]

On 19/04/2008, David Adam <david.adam.cnrs at gmail.com> wrote:
> The Sting Demo calls the function
> IDirect3DDeviceImpl_7_SetMaterial (in ddraw/device.c) with
> Mat=NULL.
> Then, this makes the function IWineD3DDeviceImpl_SetMaterial (in
> wined3d/device.c) crashes in the line
> This->updateStateBlock->material = *pMaterial;
>  So, the patch checks is the material is not null before  assignating it.
>
> This fixes a crash in The Sting demo.
>
> David Adam
>
I would like to see a few tests that prove this is the correct
behaviour (instead of eg. simply returning WINED3DERR_INVALIDCALL),
for ddraw, d3d8 and d3d9.