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/file.c b/server/file.c
index dd38e19..9000b61 100644
--- a/server/file.c
+++ b/server/file.c
@@ -80,6 +80,7 @@
     no_satisfied,                 /* satisfied */
     no_signal,                    /* signal */
     file_get_fd,                  /* get_fd */
+    no_close_handle,              /* close_handle */
     file_destroy                  /* destroy */
 };