int -> B.t Terms.unit_clause -> B.t Terms.unit_clause * int
(* relocate [maxvar] [varlist] -> [newmaxvar] * [varlist] * [relocsubst] *)
int -> B.t Terms.unit_clause -> B.t Terms.unit_clause * int
(* relocate [maxvar] [varlist] -> [newmaxvar] * [varlist] * [relocsubst] *)