RFC: anv: Enable VK_EXT_image_drm_format_modifier
The draft spec lives at http://kiwitree.net/~chadv/vulkan/#1.0-VK_EXT_image_drm_format_modifier. This extension spec has a complete, working API. I'm happy with the API, and believe it's good enough. But the spec language has some outstanding issues that prevent it from being submitted as-is to Khronos: the spec language needs more polish, and the appendix chaper has a list of incomplete TODOs.