[3546] Trivial: updated copyright date.

src/lib/dhcp/libdhcp++.cc

@@ -1,4 +1,4 @@
-// Copyright (C) 2011-2013 Internet Systems Consortium, Inc. ("ISC")
+// Copyright (C) 2011-2014 Internet Systems Consortium, Inc. ("ISC")
 //
 // Permission to use, copy, modify, and/or distribute this software for any
 // purpose with or without fee is hereby granted, provided that the above