Fix warning due to relaxed function declaration prototype

Fixes this:

libintl/libintl.c:81:13: warning: function declaration isn't a prototype [-Wstrict-prototypes]
 const char *_nl_expand_alias () { return NULL; }
             ^~~~~~~~~~~~~~~~

Signed-off-by: Yann Sionneau <ysionneau@kalray.eu>

libintl/libintl.c

@@ -78,5 +78,5 @@ char *bind_textdomain_codeset(const char *domainname, const char *codeset)
 }
 
 /* trick configure tests checking for gnu libintl, as in the copy included in gdb */
-const char *_nl_expand_alias () { return NULL; }
+const char *_nl_expand_alias (void) { return NULL; }
 int _nl_msg_cat_cntr = 0;