Added copyright

build/src/core.c

+// Copyright (c) 2004-2013 Sergey Lyubka <valenok@gmail.com>
+// Copyright (c) 2013 Cesanta Software Limited
+// All rights reserved
+//
+// This library is dual-licensed: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License version 2 as
+// published by the Free Software Foundation. For the terms of this
+// license, see <http://www.gnu.org/licenses/>.
+//
+// You are free to use this library under the terms of the GNU General
+// Public License, but WITHOUT ANY WARRANTY; without even the implied
+// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+// See the GNU General Public License for more details.
+//
+// Alternatively, you can license this library under a commercial
+// license, as set out in <http://cesanta.com/products.html>.
+
 #ifdef _WIN32
 #undef _UNICODE
 #define _MBCS