Modules: Remove _ldap._forward and _ldap._reverse

These were created only as:
forward = {}
reverse = {0: None}

The only use was the function LDAPconstant, equivalent to:

    def LDAPconstant(i):
        return reverse.get(i, i)

It looks like these were prepared for a better future, but python-ldap
has gone for years or decades without needing to actually use them.
Remove both dictionaries and the function.

Modules/LDAPObject.c

@@ -1059,7 +1059,12 @@ l_ldap_result4( LDAPObject* self, PyObject *args )
 
     pmsg = LDAPmessage_to_python( self->ldap, msg, add_ctrls, add_intermediates );
 
-    result_str = LDAPconstant( res_type );
+    if (res_type == 0) {
+        result_str = Py_None;
+        Py_INCREF(Py_None);
+    } else {
+        result_str = PyInt_FromLong( res_type );
+    }
 
     if (pmsg == NULL) {
             retval = NULL;

Modules/constants.c

@@ -6,35 +6,12 @@
 #include "lber.h"
 #include "ldap.h"
 
-static PyObject* reverse;
-static PyObject* forward;
-
-/* convert an result integer into a Python string */
-
-PyObject*
-LDAPconstant( int val ) {
-    PyObject *i = PyInt_FromLong( val );
-    PyObject *s = PyObject_GetItem( reverse, i );
-    if (s == NULL) {
-      PyErr_Clear();
-  return i;
-    }
-    Py_DECREF(i);
-    return s;
-}
-
 /* initialise the module constants */
 
 void
 LDAPinit_constants( PyObject* d )
 {
-  PyObject *zero, *author,*obj;
-
-  reverse = PyDict_New();
-  forward = PyDict_New();
-
-  PyDict_SetItemString( d, "_reverse", reverse );
-  PyDict_SetItemString( d, "_forward", forward );
+  PyObject *obj;
 
 #define add_int(d, name) \
   { \
@@ -91,10 +68,6 @@ LDAPinit_constants( PyObject* d )
 
   /* reversibles */
 
-  zero = PyInt_FromLong( 0 );
-  PyDict_SetItem( reverse, zero, Py_None );
-  Py_DECREF( zero );
-
   add_int(d,RES_BIND);
   add_int(d,RES_SEARCH_ENTRY);
   add_int(d,RES_SEARCH_RESULT);