timedated: don't make failures to write timezone_file critical

This file is not actually a requirement, so failure to write should
not be a severe problem. If that happens, print the error and just continue.

src/timedated.c

@@ -154,8 +154,11 @@ static gboolean
 set_timezone (const gchar *identifier,
               GError **error)
 {
-    if (!set_timezone_file (identifier, error))
-        return FALSE;
+    if (!set_timezone_file (identifier, error)) {
+        g_autofree gchar *timezone_filename = g_file_get_path (timezone_file);
+        g_debug ("Error setting %s: %s", timezone_filename, (*error)->message);
+        g_clear_error (error);
+    }
     if (!set_localtime_file (identifier, error))
         return FALSE;