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/src/haproxy.c b/src/haproxy.c
index 7656167..c3d6255 100644
--- a/src/haproxy.c
+++ b/src/haproxy.c
@@ -1058,6 +1058,10 @@
 	if (!global.node)
 		global.node = strdup(hostname);
 
+#ifdef USE_LUA
+	if (!hlua_post_init())
+		exit(1);
+#endif
 }
 
 static void deinit_acl_cond(struct acl_cond *cond)