kconfig: fix MAC OS X warnings in menuconfig

Signed-off-by: Sam Ravnborg <[email protected]>
Acked-by: Timur Tabi <[email protected]>
diff --git a/scripts/kconfig/mconf.c b/scripts/kconfig/mconf.c
index 734cf4f..6841e95c 100644
--- a/scripts/kconfig/mconf.c
+++ b/scripts/kconfig/mconf.c
@@ -773,7 +773,7 @@
 
 	while (1) {
 		int res;
-		char *heading;
+		const char *heading;
 
 		switch (sym_get_type(menu->sym)) {
 		case S_INT:
@@ -925,3 +925,4 @@
 
 	return 0;
 }
+