Graph Algorithms in Rayon

The Wild linker makes very extensive use of rayon for parallelism. Much of this parallelism is in the form of par_iter and friends. However, some parts of the linker don’t fit neatly because the amount of work isn’t known in advance. For example, the linker has two places where it explores a graph. When we start, we know some roots of that graph, but we don’t know all the nodes that we’ll need to…