dogfood: fix missing override

Note: the rule is disabled for pmd-xml, refs #1074

pmd-cpp/src/main/java/net/sourceforge/pmd/lang/cpp/CppTokenManager.java

@@ -25,6 +25,7 @@ public class CppTokenManager implements TokenManager {
         tokenManager = new CppParserTokenManager(new CppCharStream(source));
     }
 
+    @Override
     public Object getNextToken() {
         return tokenManager.getNextToken();
     }