Add typecast to execv call.

Declare function menu_dump.

clients/lcdexec/menu.h

@@ -46,4 +46,5 @@ int menu_sock_send(MenuEntry *me, MenuEntry *parent, int sock);
 MenuEntry *menu_find_by_id(MenuEntry *me, int id);
 const char *menu_command(MenuEntry *me);
 void menu_free(MenuEntry *me);
+void menu_dump(MenuEntry *me);