This applies on top of !656, the last three commits belong here.
-- v2: vkd3d-shader/ir: Compute the loops in the control flow graph. vkd3d-shader/ir: Add a debug buffer to struct vsir_cfg. vkd3d-shader/ir: Properly handle function-local indexable temps when flattening control flow. vkd3d-shader/ir: Dump the domination relationship. vkd3d-shader/ir: Compute the domination relationship. vkd3d-shader/ir: Dump the control flow graph in the GraphViz format. vkd3d-shader/ir: Build a representation of the control flow graph.