Update copyright years.

From-SVN: r256169
diff --git a/libgcc/unwind-compat.c b/libgcc/unwind-compat.c
index f87709d..2b099e5 100644
--- a/libgcc/unwind-compat.c
+++ b/libgcc/unwind-compat.c
@@ -1,5 +1,5 @@
 /* Backward compatibility unwind routines.
-   Copyright (C) 2004-2017 Free Software Foundation, Inc.
+   Copyright (C) 2004-2018 Free Software Foundation, Inc.
 
    This file is part of GCC.