scripted-diff: Bump copyright of files changed in 2019

-BEGIN VERIFY SCRIPT-
./contrib/devtools/copyright_header.py update ./
-END VERIFY SCRIPT-

src/validationinterface.cpp

@@ -1,5 +1,5 @@
 // Copyright (c) 2009-2010 Satoshi Nakamoto
-// Copyright (c) 2009-2018 The Bitcoin Core developers
+// Copyright (c) 2009-2019 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.