[1/3] WineD3D: Infrastructure to render swapchains to a FBO

[Stefan Dösinger]

> I think this will break color_fill_fbo
I'll investigate that, but I think if it did it would break the d3d9 tests if I force rendering to the FBO - which I did for testing.

> Out of curiosity, what would the performance impact be of always
> rendering to FBO?
I only tested it on my macs so far, because I've written this mainly to work around blitting bugs:

The performance depends on what the app is doing. I tested it with the d3d8 SDK samples, where the drawing effort is pretty small, and the present() call probably the biggest single call. Apps which do not render offscreen have a ~10% performance hit. Apps which render offscreen and need the depth blit gain about 10% performance.

That said, I think OSX always renders to a FBO behind our back, so other drivers might show different behavior.