Update Copyright headers
diff --git a/src/hb-buffer.h b/src/hb-buffer.h
index b80ce9f..e7ef087 100644
--- a/src/hb-buffer.h
+++ b/src/hb-buffer.h
@@ -1,7 +1,7 @@
 /*
- * Copyright (C) 1998-2004  David Turner and Werner Lemberg
- * Copyright (C) 2004,2007,2009  Red Hat, Inc.
- * Copyright (C) 2011  Google, Inc.
+ * Copyright © 1998-2004  David Turner and Werner Lemberg
+ * Copyright © 2004,2007,2009  Red Hat, Inc.
+ * Copyright © 2011  Google, Inc.
  *
  *  This is part of HarfBuzz, a text shaping library.
  *