wined3d: Avoid crashing when ProcessVertices is called with NULL vertex declaration

[H. Verbeet]

On 04/09/06, Paul Chitescu <paulc at voip.null.ro> wrote:
> Well, what do you thing it did before at the line
>     if(SrcImpl->vbo) {
>         ...
> if SrcImpl is NULL?
>
> I don't understand what the code does but every part of it depends on
> having a non-NULL SrcImpl. I think screaming bloody murder but continuing
> is better than crashing.
Well, no, crashing is preferred over continuing incorrectly. I would
have to look into how the function is supposed to work in d3d8, but we
should probably figure out where to get SrcImpl in case of d3d8.