kconfig: constify file name

Signed-off-by: Arnaud Lacombe <lacombar@gmail.com>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Michal Marek <mmarek@suse.cz>

scripts/kconfig/lkc.h

@@ -76,7 +76,7 @@ FILE *zconf_fopen(const char *name);
 void zconf_initscan(const char *name);
 void zconf_nextfile(const char *name);
 int zconf_lineno(void);
-char *zconf_curname(void);
+const char *zconf_curname(void);
 
 /* conf.c */
 void xfgets(char *str, int size, FILE *in);