[gnome-control-center] network: Fix crash when changing IPv4 DNS

[Bastien Nocera <hadess src gnome org>]

commit ca47ff295a1e45598068201633aa2bd0d8fd5b29
Author: Bastien Nocera <hadess hadess net>
Date:   Tue Sep 13 11:45:20 2016 +0200

    network: Fix crash when changing IPv4 DNS
    
    The dns_servers GStrv was not NULL-terminated because we forgot to
    append a NULL item to the GPtrArray that we used to construct it.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=771251

 panels/network/connection-editor/ce-page-ip4.c |    9 ++++++++-
 1 files changed, 8 insertions(+), 1 deletions(-)
---
diff --git a/panels/network/connection-editor/ce-page-ip4.c b/panels/network/connection-editor/ce-page-ip4.c
index 2645603..bcc7e0b 100644
--- a/panels/network/connection-editor/ce-page-ip4.c
+++ b/panels/network/connection-editor/ce-page-ip4.c
@@ -787,6 +787,13 @@ ui_to_setting (CEPageIP4 *page)
         }
         g_list_free (children);
 
+        if (dns_servers->len == 0) {
+                g_ptr_array_free (dns_servers, TRUE);
+                dns_servers = NULL;
+        } else {
+                g_ptr_array_add (dns_servers, NULL);
+        }
+
         routes = g_ptr_array_new_with_free_func (g_object_unref);
         if (g_str_equal (method, NM_SETTING_IP4_CONFIG_METHOD_AUTO) ||
             g_str_equal (method, NM_SETTING_IP4_CONFIG_METHOD_MANUAL))
@@ -878,7 +885,7 @@ ui_to_setting (CEPageIP4 *page)
         g_object_set (page->setting,
                       NM_SETTING_IP_CONFIG_METHOD, method,
                       NM_SETTING_IP_CONFIG_ADDRESSES, addresses,
-                      NM_SETTING_IP_CONFIG_DNS, dns_servers->pdata,
+                      NM_SETTING_IP_CONFIG_DNS, dns_servers ? dns_servers->pdata : NULL,
                       NM_SETTING_IP_CONFIG_ROUTES, routes,
                       NM_SETTING_IP_CONFIG_IGNORE_AUTO_DNS, ignore_auto_dns,
                       NM_SETTING_IP_CONFIG_IGNORE_AUTO_ROUTES, ignore_auto_routes,