PostSolver.EqConstrSysFromStartEqConstrSysJoin start values into right-hand sides. This simplifies start handling in Make.
module S : StartEqConstrSystype v = S.vtype d = S.dmodule Var = S.VarVariables must be hashable, comparable, etc.
module Dom = S.DomValues must form a lattice.
val increment : Analyses.increment_dataData used for incremental analysis