CfgTools.SCCStrongly connected component.
type t = {nodes : unit NH.t;Set of nodes in SCC, mutated during computeSCCs.
next : (MyCFG.edges * MyCFG.node) list NH.t;Successor edges from this SCC to another SCC, mutated during computeSCCs.
prev : (MyCFG.edges * MyCFG.node) list NH.t;Predecessor edges from another SCC to this SCC, mutated during computeSCCs.
}