add d3d12 gallium driver
Finally, here it is. The initial code for the D3D12 gallium driver used in Microsoft's GLon12 translation layer.
This is the result of a lot of commits from our downstream branch, which we will retire as soon as all of this work has landed.
This is just the initial driver, though. Once this has landed, we will submit a few more merge-requests, adding the following:
- Code to use DXGI swapchains for zero-copy winsys integration
- OpenCL C compiler API that will be used in Microsoft's CLon12 OpenCL implementation
- Wire up CI builds
Because of the mentioned patches, I'm hoping to land this without major changes to the driver, as this will make the upstreaming process smoother.
That being said, comments are welcome!