omit internal attributes in residual goals when using taut/2
Examples:
?- taut(X=:=X,1).
clpb:sat(X=:=X)
;  false.
?- taut(X=\=X,0).
clpb:sat(X=:=X)
;  false.
@@ -1558,9 +1558,10 @@ sats([]) --> [].
sats([A|As]) --> [clpb:sat(A)], sats(As).
booleans([]) --> [].
-booleans([B|Bs]) --> boolean(B), { del_clpb(B) }, booleans(Bs).
+booleans([B|Bs]) --> boolean(B), booleans(Bs).
boolean(Var) -->
+ { del_clpb(Var) },
( { get_attr(Var, clpb_omit_boolean, true) } -> []
; [clpb:sat(Var =:= Var)]
).
