We never supported, and we should never need to support more than 8 user
clip planes in wined3d.

OpenGL drivers do not expose more than 8 clip distances. Similarly,
other APIs, D3D10, D3D11 and D3D12 provide exactly 8 clip distances.
Signed-off-by: Józef Kucia <jkucia@codeweavers.com>
Signed-off-by: Henri Verbeet <hverbeet@codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>