254: Specify expected structure for draw_indirect and draw_indexed_indirect r=kvark a=lachlansneff ~~Based on https://www.khronos.org/opengl/wiki/Vertex_Rendering#Indirect_rendering.~~ Turns out the opengl docs are wrong. Based on https://www.khronos.org/registry/vulkan/specs/1.2-extensions/man/html/VkDrawIndirectCommand.html. Co-authored-by: Lachlan Sneff <lachlan.sneff@gmail.com>