Fix nonstandard TAILQ_FOREACH_REVERSE() definition

Every current BSD system providing TAILQ_* macros define
TAILQ_FOREACH_REVERSE in this order:

TAILQ_FOREACH_REVERSE(var, head, field, headname)

However, libevent defines it in another order:

TAILQ_FOREACH_REVERSE(var, head, headname, field)

Here's a trivial patch to have libevent compatible with stock queue.h headers.

-Frank.

[From sourceforge patch 2995179. codesearch.google.com confirms that
the only people defining TAILQ_FOREACH_REVERSE our way are people
using it in a compatibility header like us.  Did we copy this from
OpenSSH or something?]

-Nick

compat/sys/queue.h

@@ -306,7 +306,7 @@ struct {								\
 	    (var) != TAILQ_END(head);					\
 	    (var) = TAILQ_NEXT(var, field))
 
-#define TAILQ_FOREACH_REVERSE(var, head, field, headname)		\
+#define TAILQ_FOREACH_REVERSE(var, head, headname, field)		\
 	for((var) = TAILQ_LAST(head, headname);				\
 	    (var) != TAILQ_END(head);					\
 	    (var) = TAILQ_PREV(var, headname, field))

event.c

@@ -2361,7 +2361,7 @@ insert_common_timeout_inorder(struct common_timeout_list *ctl,
 	 * the end of 'ev' to find the right insertion point.
 	 */
 	TAILQ_FOREACH_REVERSE(e, &ctl->events,
-	    ev_timeout_pos.ev_next_with_common_timeout, event_list) {
+	    event_list, ev_timeout_pos.ev_next_with_common_timeout) {
 		/* This timercmp is a little sneaky, since both ev and e have
 		 * magic values in tv_usec.  Fortunately, they ought to have
 		 * the _same_ magic values in tv_usec.  Let's assert for that.