Hull Shaders contain two functions instead of just one, so all the algorithms that require computing a CFG need to be run twice. Here we refactor the code so that this can be done more easily.
This MR is relatively long, but it is essentially just moving code around, so hopefully it is not too difficult to review anyway.
-- v4: vkd3d-shader/ir: Split handling jumps when emitting a structured program. vkd3d-shader/ir: Split handling selections when emitting a structured program. vkd3d-shader/ir: Split handling loops when emitting a structured program. vkd3d-shader/ir: Split handling blocks when emitting a structured program. vkd3d-shader/ir: Refactor declaration emission outside of the CFG structure. vkd3d-shader/ir: Split undominated SSA materialization. vkd3d-shader/ir: Split program structurization.