fix an aliasing issue

Changes

@@ -3,6 +3,7 @@ Revision history for libev, a high-performance and full-featured event loop.
 	- use 1-based heaps, simplifies code, reduces codesize, makes
           for better cache-efficiency and increases memory requirements
           by up to two pointers/loop.
+        - fix a potential aliasing issue.
 
 3.31 Wed Apr 16 20:45:04 CEST 2008
 	- added last minute fix for ev_poll.c by Brandon Black.

ev.c

@@ -327,6 +327,7 @@ typedef ev_watcher *W;
 typedef ev_watcher_list *WL;
 typedef ev_watcher_time *WT;
 
+#define ev_active(w) ((W)(w))->active
 #define ev_at(w) ((WT)(w))->at
 
 #if EV_USE_MONOTONIC
@@ -1940,7 +1941,7 @@ ev_timer_again (EV_P_ ev_timer *w)
     }
   else if (w->repeat)
     {
-      w->at = w->repeat;
+      ev_at (w) = w->repeat;
       ev_timer_start (EV_A_ w);
     }
 }