Add a missing prototype until libevent people catch up.

git-svn-id: http://www.varnish-cache.org/svn/trunk@105 d4fa192b-c00b-0410-8231-f00ffab90ce4

contrib/libevent/event.h

@@ -260,6 +260,7 @@ struct bufferevent {
 struct bufferevent *bufferevent_new(int fd,
     evbuffercb readcb, evbuffercb writecb, everrorcb errorcb, void *cbarg);
 int bufferevent_priority_set(struct bufferevent *bufev, int pri);
+int bufferevent_base_set(struct event_base *base, struct bufferevent *bufev);
 void bufferevent_free(struct bufferevent *bufev);
 int bufferevent_write(struct bufferevent *bufev, void *data, size_t size);
 int bufferevent_write_buffer(struct bufferevent *bufev, struct evbuffer *buf);