C++: Add missing override annotations

Author: jbj

cpp/ql/src/semmle/code/cpp/Class.qll

@@ -566,7 +566,7 @@ class Class extends UserType {
    * The alignment of this type in bytes (on the machine where facts were
    * extracted).
    */
-  int getAlignment() { usertypesize(underlyingElement(this),_,result) }
+  override int getAlignment() { usertypesize(underlyingElement(this),_,result) }
 
   /**
    * Holds if this class is constructed from another class as a result of

cpp/ql/src/semmle/code/cpp/File.qll

@@ -162,7 +162,7 @@ abstract class Container extends Locatable, @container {
    *
    * This is the absolute path of the container.
    */
-  string toString() {
+  override string toString() {
     result = getAbsolutePath()
   }
 }