[gnome-contacts] Contact: use const string[] for sorted properties.

[Niels De Graef <nielsdg src gnome org>]

commit d90a458b6f3deb30020b4ab769a67eb78d2c156f
Author: Niels De Graef <nielsdegraef gmail com>
Date:   Tue Feb 13 20:56:10 2018 +0100

    Contact: use const string[] for sorted properties.

 src/contacts-contact.vala | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/src/contacts-contact.vala b/src/contacts-contact.vala
index 8036803..5006a64 100644
--- a/src/contacts-contact.vala
+++ b/src/contacts-contact.vala
@@ -579,7 +579,7 @@ public class Contacts.Contact : GLib.Object  {
     return store.display_name;
   }
 
-  public static string[] sorted_properties = { "email-addresses" , "phone-numbers" , "im-addresses", "urls", 
"nickname", "birthday", "notes", "postal-addresses" };
+  public const string[] sorted_properties = { "email-addresses" , "phone-numbers" , "im-addresses", "urls", 
"nickname", "birthday", "notes", "postal-addresses" };
 
   public static string []sort_persona_properties (string [] props) {
     CompareDataFunc<string> compare_properties = (a, b) =>