server: Add support for storing an event to signal upon async I/O completion.
diff --git a/server/protocol.def b/server/protocol.def
index 145fbeb..3d0618a 100644
--- a/server/protocol.def
+++ b/server/protocol.def
@@ -178,6 +178,7 @@
     void           *callback;      /* client-side callback to call upon end of async */
     void           *iosb;          /* I/O status block in client addr space */
     void           *arg;           /* opaque user data to pass to callback */
+    obj_handle_t    event;         /* event to signal when done */
 } async_data_t;
 
 /* structures for extra message data */