Added a close_handle method to the object operations, and use it to
implement registry notifications and the strange behavior of
CloseHandle on winstation/desktop handles.

diff --git a/server/event.c b/server/event.c
index fa1dbbf..3445185 100644
--- a/server/event.c
+++ b/server/event.c
@@ -53,6 +53,7 @@
     event_satisfied,           /* satisfied */
     event_signal,              /* signal */
     no_get_fd,                 /* get_fd */
+    no_close_handle,           /* close_handle */
     no_destroy                 /* destroy */
 };