[gtk+/gtk-3-8] printing: Don't crash when printer-state-message not provided

[Marek Kašík <mkasik src gnome org>]

commit 7e86d69854fdf50fc99f0314922898e63ff1d806
Author: Marek Kasik <mkasik redhat com>
Date:   Mon May 6 13:43:18 2013 +0200

    printing: Don't crash when printer-state-message not provided
    
    Check whether "printer-state-message" was returned before its
    usage.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=699750

 modules/printbackends/cups/gtkprintbackendcups.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/modules/printbackends/cups/gtkprintbackendcups.c 
b/modules/printbackends/cups/gtkprintbackendcups.c
index 80d868c..0093c31 100644
--- a/modules/printbackends/cups/gtkprintbackendcups.c
+++ b/modules/printbackends/cups/gtkprintbackendcups.c
@@ -2320,7 +2320,7 @@ set_info_state_message (PrinterSetupInfo *info)
 
       if (info->reason_level >= GTK_PRINTER_STATE_LEVEL_WARNING)
         {
-          if (strlen (info->state_msg) == 0)
+          if (info->state_msg == NULL || info->state_msg[0] == '\0')
             {
               g_free (info->state_msg);
               info->state_msg = reason_msg_desc;