Use time_t to pass to ctime(). This isn't 2038 clean, but fixing that
would be too much patching.

Index: src/preferences/ario-server-preferences.c
--- src/preferences/ario-server-preferences.c.orig
+++ src/preferences/ario-server-preferences.c
@@ -169,7 +169,7 @@ ario_server_preferences_sync_server (ArioServerPrefere
         int crossfadetime;
         int state;
         gboolean updating;
-        long last_update;
+        time_t last_update;
         gchar *last_update_char;
         GtkTreeIter iter;
         GSList *tmp;
