Remove unused quantifier_exprt default constructor

tautschnig · tautschnig · commit 91d64fbe08fb · 2018-09-26T10:13:59.000Z
It made use of the deprecated symbol_exprt() constructor and was never used
anyway.
diff --git a/src/util/std_expr.h b/src/util/std_expr.h
@@ -4565,11 +4565,6 @@ inline void validate_expr(const let_exprt &value)
 class quantifier_exprt:public binary_predicate_exprt
 {
 public:
-  explicit quantifier_exprt(const irep_idt &_id):binary_predicate_exprt(_id)
-  {
-    op0()=symbol_exprt();
-  }
-
   quantifier_exprt(
     const irep_idt &_id,
     const symbol_exprt &_symbol,
