chore: drop some dead code (#259)

This avoids a warning about the deprecated Std.BitVec

SSA/Core/Util.lean

@@ -113,22 +113,19 @@ instance [inst : Cli.ParseableType τ] {n : ℕ} : Cli.ParseableType (Vector τ
     else
       none
 
-
-@[simp] abbrev Std.BitVec.width : Std.BitVec w → Nat := fun _ => w
-
 /-- productsList [xs, ys] = [(x, y) for x in xs for y in ys],
 extended to arbitary number of arrays. -/
 def productsList : List (List α) -> List (List α)
 | [] => [[]] -- empty product returns empty tuple.
-| (xs::xss) => Id.run do 
+| (xs::xss) => Id.run do
   let mut out := []
   let xss' := productsList xss -- make tuples of the other columns.
   for x in xs do  -- for every element in this column, take product with all other tuples.
     out := out.append (xss'.map (fun xs => x :: xs))
   return out
-    
+
 example : productsList [["a"], ["x", "y", "z"]] = [["a", "x"], ["a", "y"], ["a", "z"]] := rfl
-example : productsList [["a"], ["p", "q"], ["x", "y", "z"]] = 
+example : productsList [["a"], ["p", "q"], ["x", "y", "z"]] =
   [["a", "p", "x"], ["a", "p", "y"], ["a", "p", "z"],
    ["a", "q", "x"], ["a", "q", "y"], ["a", "q", "z"]] := rfl