[vala] x11: make WindowAttributes.screen unowned

[Luca Bruno <lucabru src gnome org>]

commit 8a37d96da987a9379b6993d4e959cfc7acd42aa9
Author: Luca Bruno <lucabru src gnome org>
Date:   Fri Feb 27 18:10:17 2015 +0100

    x11: make WindowAttributes.screen unowned
    
    Fixes bug 745133

 vapi/x11.vapi |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/vapi/x11.vapi b/vapi/x11.vapi
index aaa3fea..b044803 100644
--- a/vapi/x11.vapi
+++ b/vapi/x11.vapi
@@ -598,7 +598,7 @@ namespace X {
                public long your_event_mask;    /* my event mask */
                public long do_not_propagate_mask; /* set of events that should not propagate */
                public bool override_redirect;  /* boolean value for override-redirect */
-               public Screen screen;           /* back pointer to correct screen */
+               public unowned Screen screen;   /* back pointer to correct screen */
        }
 
        [CCode (cname = "ParentRelative")]