[gtk+/gtk-3-22] cups: Warn only once if colord is not available

[Matthias Clasen <matthiasc src gnome org>]

commit 0eaa76a032a42b612387cf06d7a12304b95d8ac2
Author: Matthias Clasen <mclasen redhat com>
Date:   Sun Dec 17 17:09:55 2017 -0500

    cups: Warn only once if colord is not available
    
    No need to keep complaining about this.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=791650

 modules/printbackends/cups/gtkprintercups.c |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletions(-)
---
diff --git a/modules/printbackends/cups/gtkprintercups.c b/modules/printbackends/cups/gtkprintercups.c
index 068aba7..525382a 100644
--- a/modules/printbackends/cups/gtkprintercups.c
+++ b/modules/printbackends/cups/gtkprintercups.c
@@ -539,12 +539,17 @@ colord_client_connect_cb (GObject *source_object,
   gboolean ret;
   GError *error = NULL;
   GtkPrinterCups *printer = GTK_PRINTER_CUPS (user_data);
+  static gboolean colord_warned = FALSE;
 
   ret = cd_client_connect_finish (CD_CLIENT (source_object),
                                   res, &error);
   if (!ret)
     {
-      g_warning ("failed to contact colord: %s", error->message);
+      if (!colord_warned)
+        {
+          g_warning ("failed to contact colord: %s", error->message);
+          colord_warned = TRUE;
+        }
       g_error_free (error);
     }