Make POL equals method final

Author: msimacek

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/objects/object/PythonObjectLibrary.java

@@ -465,7 +465,7 @@ public boolean equalsWithState(Object receiver, Object other, PythonObjectLibrar
     /**
      * @see #equalsWithState
      */
-    public boolean equals(Object receiver, Object other, PythonObjectLibrary otherLibrary) {
+    public final boolean equals(Object receiver, Object other, PythonObjectLibrary otherLibrary) {
         return equalsWithState(receiver, other, otherLibrary, null);
     }