Update copyright years.

From-SVN: r232055
diff --git a/libitm/method-serial.cc b/libitm/method-serial.cc
index 261644e..82d407d 100644
--- a/libitm/method-serial.cc
+++ b/libitm/method-serial.cc
@@ -1,4 +1,4 @@
-/* Copyright (C) 2008-2015 Free Software Foundation, Inc.
+/* Copyright (C) 2008-2016 Free Software Foundation, Inc.
    Contributed by Richard Henderson <rth@redhat.com>.
 
    This file is part of the GNU Transactional Memory Library (libitm).