C++: Add 'DataFlow::indirectExpr' predicates since Coding Standards now depend on such a predicate.

Author: MathiasVP

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/DataFlowNodes.qll

@@ -946,6 +946,24 @@ module Public {
    */
   ExprNode exprNode(Expr e) { result.getExpr(_) = e }
 
+  /**
+   * Gets the `Node` corresponding to the value after `indirection` number of
+   * dereferences of `e` or any of its conversions. There is no result if `e`
+   * is a `Conversion`. For data flowing _out of_ an expression, like when an
+   * argument is passed by reference, use
+   * `definitionByReferenceNodeFromArgument` instead.
+   */
+  IndirectExprNode indirectExprNode(Expr e, int indirection) { result.getExpr(indirection) = e }
+
+  /**
+   * Gets the `Node` corresponding to the value after any number of
+   * dereferences of `e` or any of its conversions. There is no result if `e`
+   * is a `Conversion`. For data flowing _out of_ an expression, like when an
+   * argument is passed by reference, use
+   * `definitionByReferenceNodeFromArgument` instead.
+   */
+  IndirectExprNode indirectExprNode(Expr e) { result = indirectExprNode(e, _) }
+
   /**
    * Gets the `Node` corresponding to the value of evaluating `e`. Here, `e` may
    * be a `Conversion`. For data flowing _out of_ an expression, like when an