remove clpb_max/1 attribute for residual goal projection

Example:

    ?- sat(A+B), weighted_maximum([1,1], [A,B], Max).
       A = 1, B = 1, Max = 2.

src/lib/clpb.pl

@@ -1656,6 +1656,10 @@ attribute_goals(Var) -->
             booleans(RestVs)
         ;   boolean(Var)  % the variable may have occurred only in taut/2
         ).
+attribute_goals(Var) -->
+        { get_atts(Var, clpb_max(_)),
+          !,
+          put_atts(Var, -clpb_max(_)) }.
 attribute_goals(Var) -->
         { get_atts(Var, clpb_bdd(BDD)),
           ground(BDD),