posix: upgrade libevent from 1.4.7 to 1.4.13

third_party/libevent/event-internal.h

Index: third_party/libevent/event-internal.h
diff --git a/third_party/libevent/event-internal.h b/third_party/libevent/event-internal.h
index 93ac5687e4da69c55946e3bd6a8987d80485d7eb..b7f00402be536344d51a4f516b81c216904f2e8f 100644
--- a/third_party/libevent/event-internal.h
+++ b/third_party/libevent/event-internal.h
@@ -71,7 +71,7 @@ struct event_base {
 };
 
 /* Internal use only: Functions that might be missing from <sys/queue.h> */
-#if !defined(HAVE_TAILQFOREACH) || defined(__QUENTIN_BUILD__)
+#ifndef HAVE_TAILQFOREACH
 #define	TAILQ_FIRST(head)		((head)->tqh_first)
 #define	TAILQ_END(head)			NULL
 #define	TAILQ_NEXT(elm, field)		((elm)->field.tqe_next)
@@ -85,15 +85,15 @@ struct event_base {
 	*(listelm)->field.tqe_prev = (elm);				\
 	(listelm)->field.tqe_prev = &(elm)->field.tqe_next;		\
 } while (0)
-#define TAILQ_LAST(head, headname) \
-	(*(((struct headname *)((head)->tqh_last))->tqh_last))
-#define TAILQ_EMPTY(head)	((head)->tqh_first == NULL)
 #endif /* TAILQ_FOREACH */
 
 int _evsignal_set_handler(struct event_base *base, int evsignal,
 			  void (*fn)(int));
 int _evsignal_restore_handler(struct event_base *base, int evsignal);
 
+/* defined in evutil.c */
+const char *evutil_getenv(const char *varname);
+
 #ifdef __cplusplus
 }
 #endif