All D3D versions seem to basically guarantee invariance for the vertex
position at the very least. In practice, desktop GL implementations
also do the same.
That's not necessarily the case for tile based renderers, where the
cost of providing invariance might be non negligible. We want this
behavior though, so let's ask for it explicitly.

Based on a patch by Stefan Dösinger.
Signed-off-by: Matteo Bruni <mbruni@codeweavers.com>
Signed-off-by: Henri Verbeet <hverbeet@codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>