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/thread.c b/server/thread.c
index 3fb06c5..b021dc0 100644
--- a/server/thread.c
+++ b/server/thread.c
@@ -94,6 +94,7 @@
     no_satisfied,               /* satisfied */
     no_signal,                  /* signal */
     no_get_fd,                  /* get_fd */
+    no_close_handle,            /* close_handle */
     destroy_thread              /* destroy */
 };