WineD3D: heap corruption in d3dfmt_convert_surface

[Markus Amsler]

I have (finally!) found the heap corruption in bf1942:
Small surfaces have a pitch of 4 and a width <4. This results in pitch*4
> outpitch in IWineD3DSurfaceImpl_LoadTexture:1844. Afterwards the heap 
> gets corrupted in d3dfmt_convert_surface:1654. The attached patch fixes 
> the problem.
> I'm quite sure this fix is ugly, Suggestions?

Markus