C++: Address review comments

Author: jketema

cpp/ql/lib/semmle/code/cpp/models/implementations/Scanf.qll

@@ -71,9 +71,7 @@ abstract private class ScanfFunctionModel extends ArrayFunction, TaintFunction,
 /**
  * The standard function `scanf` and its assorted variants
  */
-private class ScanfModel extends ScanfFunctionModel, LocalFlowSourceFunction {
-  ScanfModel() { this instanceof Scanf }
-
+private class ScanfModel extends ScanfFunctionModel, LocalFlowSourceFunction instanceof Scanf {
   override predicate hasLocalFlowSource(FunctionOutput output, string description) {
     output.isParameterDeref(any(int i | i >= this.getArgsStartPosition())) and
     description = "Value read by " + this.getName()
@@ -83,9 +81,7 @@ private class ScanfModel extends ScanfFunctionModel, LocalFlowSourceFunction {
 /**
  * The standard function `fscanf` and its assorted variants
  */
-private class FscanfModel extends ScanfFunctionModel, RemoteFlowSourceFunction {
-  FscanfModel() { this instanceof Fscanf }
-
+private class FscanfModel extends ScanfFunctionModel, RemoteFlowSourceFunction instanceof Fscanf {
   override predicate hasRemoteFlowSource(FunctionOutput output, string description) {
     output.isParameterDeref(any(int i | i >= this.getArgsStartPosition())) and
     description = "Value read by " + this.getName()