WineD3D: Make CreateCubeTexture fail when not supported

[Felix Nawothnig]

Duane Clark wrote:
> On a Matrox G550, Win2k, crosscompiled on Linux with MingW:
> 
> I:\dlls\d3d8\tests>d3d8_crosstest texture
> texture.c:122:texture caps: 0x000041c7
> texture.c:110:pool=0 hr=0x8876086c
> texture.c:110:pool=1 hr=0x8876086c
> texture.c:110:pool=2 hr=0x8876086c
> texture.c:110:pool=3 hr=0x00000000
> texture: 57 tests executed (0 marked as todo, 0 failures), 0 skipped.

Thanks. Guess the patch is okay to commit then.