Import libconfig

Bug: 191918323
Test: presubmit pass
Change-Id: I9ad41a8a77d8f9e837e5b89c8b45f95afb961d96
diff --git a/lib/libconfig.hh b/lib/libconfig.hh
new file mode 100644
index 0000000..a3257d0
--- /dev/null
+++ b/lib/libconfig.hh
@@ -0,0 +1,23 @@
+/* ----------------------------------------------------------------------------
+   libconfig - A structured configuration file parsing library
+   Copyright (C) 2005-2018  Mark A Lindner
+
+   This file is part of libconfig.
+
+   This library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public License
+   as published by the Free Software Foundation; either version 2.1 of
+   the License, or (at your option) any later version.
+
+   This library is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with this library; if not, write to the Free Software
+   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307  USA
+   ----------------------------------------------------------------------------
+*/
+
+#include <libconfig.h++>