build: scripts/config - update to kconfig-v6.6.16

The main goal here is to keep this close to upstream.

Changes include:
 - allow symbols implied by y to become m
 - make 'imply' obey the direct dependency
 - allow only 'config', 'comment', and 'if' inside 'choice'
 - qconf: make search fully work again on split mode
 - qconf: navigate menus on hyperlinks
 - remove '---help---' support
 - qconf: allow to edit "int", "hex", "string" menus in-place
 - qconf: drop Qt4 support
 - nconf: fix core dump when searching in empty menu
 - nconf: stop endless search loops
 - Create links to main menu items in search
 - fix segmentation fault in menuconfig search
 - nconf: Add search jump feature
 - port qconf to work with Qt6 in addition to Qt5
 - fix possible buffer overflow
 - fix memory leak from range properties

Signed-off-by: Eneas U de Queiroz <cotequeiroz@gmail.com>

scripts/config/util.c

@@ -74,7 +74,7 @@ void str_printf(struct gstr *gs, const char *fmt, ...)
 }
 
 /* Retrieve value of growable string */
-const char *str_get(struct gstr *gs)
+char *str_get(struct gstr *gs)
 {
 	return gs->s;
 }