[gnome-control-center] network: Fix freeing const pointer

[Bastien Nocera <hadess src gnome org>]

commit 3b283b78b0f3e6b8a26d117c4c47cfea455385fa
Author: Bastien Nocera <hadess hadess net>
Date:   Tue May 26 13:32:50 2015 +0200

    network: Fix freeing const pointer
    
    From coverity:
    gnome-control-center-3.14.5/panels/network/connection-editor/firewall-helpers.c:75:9: warning: passing 
argument 1 of 'g_free' discards 'const' qualifier from pointer target type [enabled by default]
    
    https://bugzilla.gnome.org/show_bug.cgi?id=749897

 .../network/connection-editor/firewall-helpers.c   |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/panels/network/connection-editor/firewall-helpers.c 
b/panels/network/connection-editor/firewall-helpers.c
index 593ce9a..9d8357c 100644
--- a/panels/network/connection-editor/firewall-helpers.c
+++ b/panels/network/connection-editor/firewall-helpers.c
@@ -25,7 +25,7 @@
 #include "firewall-helpers.h"
 
 typedef struct {
-        const gchar *zone;
+        gchar *zone;
         GtkWidget *combo;
 } GetZonesReplyData;