MINOR: lua: post initialisation bindings

This system permits to execute some lua function after than HAProxy
complete his initialisation. These functions are executed between
the end of the configuration parsing and check and the begin of the
scheduler.
diff --git a/include/types/hlua.h b/include/types/hlua.h
index b2c3997..d05f59c 100644
--- a/include/types/hlua.h
+++ b/include/types/hlua.h
@@ -41,4 +41,12 @@
 	struct task *task; /* The task to be wake if an event occurs. */
 };
 
+/* This is a part of the list containing references to functions
+ * called at the initialisation time.
+ */
+struct hlua_init_function {
+	struct list l;
+	int function_ref;
+};
+
 #endif /* _TYPES_HLUA_H */