Update copyright years.

From-SVN: r256169
diff --git a/libgomp/oacc-parallel.c b/libgomp/oacc-parallel.c
index a8cff9e4..a71b399 100644
--- a/libgomp/oacc-parallel.c
+++ b/libgomp/oacc-parallel.c
@@ -1,4 +1,4 @@
-/* Copyright (C) 2013-2017 Free Software Foundation, Inc.
+/* Copyright (C) 2013-2018 Free Software Foundation, Inc.
 
    Contributed by Mentor Embedded.