build: scripts/config - update to kconfig-v5.6

Major changes include:
 - Much more readable reverse dependencies separated in groups
 - Improved recursive dependency report
 - More readable .config files: add comments to signal end of menus
 - More warnings for incorrect Config.in entries, such as a 'choice'
   default not contained in the 'choice'
 - Hability to properly display pseudographics with non-latin locales
 - Recursive dependencies can optionally be treated as errors

Changes from failed dcf3e63a35 attempt:
 - Recursive dependencies are treated as warnings by default
 - The option to treat them as errors is implemented as a command-line
   flag to scripts/config/conf instead of a compile-time definition
 - fixed handling of select with umnet dependencies

Cc: Petr Štetiar <ynezz@true.cz>
Cc: Jo-Philip Wich <jow@mein.io>
Signed-off-by: Eneas U de Queiroz <cotequeiroz@gmail.com>

scripts/config/qconf.h

@@ -1,6 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Copyright (C) 2002 Roman Zippel <zippel@linux-m68k.org>
- * Released under the terms of the GNU GPL v2.0.
  */
 
 #include <QTextBrowser>
@@ -291,6 +291,7 @@ protected:
 class ConfigMainWindow : public QMainWindow {
 	Q_OBJECT
 
+	char *configname;
 	static QAction *saveAction;
 	static void conf_changed(void);
 public: