D3D11/OpenCL interop

[Beyley]

there's a KHR extension to opencl for D3D11 to OpenCL interop
http://man.opencl.org/cl_khr_d3d11_sharing.html
We should support that in our box blur

[Eeveelution]

wouldn't it be better to just use d3d11 compute for it? other than saving some code idk if its the best idea to create a whole OpenCL device alongside a d3d11 device for the sake of a box blur, cuz i thought that the opencl stuff was meant as a fallback instead of the main thing, same goes for the other apis, not just d3d11

i explicitly remember us talking about having opencl support for those devices (of which there are alot) that support up to GL 3.3 which doesnt have compute, but also support opencl 1.1 which would be how those gpus would get hardware accelerated box blur, also from what i've read, this extension is for opencl 2.1 which is way past our version target, and I don't think we should do a """feature level""" (<- i still think this naming is stupid when they arent levels theyre just features that dont layer on top of each other at all) type system for OpenCL aswell for something thats just a box blur + maybe some more effects