Add three prototypes for functions in history.h to shut up gcc -Wall.
diff --git a/Modules/readline.c b/Modules/readline.c
index 0148206..a797d29 100644
--- a/Modules/readline.c
+++ b/Modules/readline.c
@@ -34,6 +34,9 @@
 extern int rl_bind_key_in_map(int, Function *, Keymap);
 extern int rl_initialize(void);
 extern int add_history(char *);
+extern int read_history(char *);
+extern int write_history(char *);
+extern int history_truncate_file(char *, int);
 extern Function *rl_event_hook;
 #endif