C++: fix (no string representation) for ConstructorInit

Author: IdrissRio

cpp/ql/lib/semmle/code/cpp/exprs/Call.qll

@@ -504,6 +504,8 @@ class VacuousDestructorCall extends Expr, @vacuous_destructor_call {
  */
 class ConstructorInit extends Expr, @ctorinit {
   override string getAPrimaryQlClass() { result = "ConstructorInit" }
+
+  override string toString() { result = "constructor init" }
 }
 
 /**
@@ -512,6 +514,8 @@ class ConstructorInit extends Expr, @ctorinit {
  */
 class ConstructorBaseInit extends ConstructorInit, ConstructorCall {
   override string getAPrimaryQlClass() { result = "ConstructorBaseInit" }
+
+  override string toString() { result = "call to " + this.getTarget().getName() }
 }
 
 /**