[mutter] x11-selection: Plug MetaX11SelectionOutputStream leak

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 802309caf9b2de4ac0efb2eb720a195c0c3f0c12
Author: Sebastian Keller <skeller src gnome org>
Date:   Sun Jan 5 02:20:18 2020 +0100

    x11-selection: Plug MetaX11SelectionOutputStream leak
    
    https://gitlab.gnome.org/GNOME/mutter/merge_requests/991

 src/x11/meta-x11-selection.c | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/src/x11/meta-x11-selection.c b/src/x11/meta-x11-selection.c
index 882b43297..5332e9d54 100644
--- a/src/x11/meta-x11-selection.c
+++ b/src/x11/meta-x11-selection.c
@@ -116,6 +116,7 @@ write_mimetypes_cb (GOutputStream *stream,
 
   g_output_stream_write_bytes_finish (stream, res, &error);
   g_output_stream_close (stream, NULL, NULL);
+  g_object_unref (stream);
 
   if (error)
     {