Update copyright years.

From-SVN: r256169
diff --git a/libgcc/mkheader.sh b/libgcc/mkheader.sh
index ebf05f2..f44bc61 100755
--- a/libgcc/mkheader.sh
+++ b/libgcc/mkheader.sh
@@ -1,6 +1,6 @@
 #! /bin/sh
 
-# Copyright (C) 2001-2017 Free Software Foundation, Inc.
+# Copyright (C) 2001-2018 Free Software Foundation, Inc.
 # This file is part of GCC.
 
 # GCC is free software; you can redistribute it and/or modify