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/semaphore.c b/server/semaphore.c
index 7886842..64c3447 100644
--- a/server/semaphore.c
+++ b/server/semaphore.c
@@ -53,6 +53,7 @@
     semaphore_satisfied,           /* satisfied */
     semaphore_signal,              /* signal */
     no_get_fd,                     /* get_fd */
+    no_close_handle,               /* close_handle */
     no_destroy                     /* destroy */
 };