Add a simple fuzz test for jsoncpp.

src/test_lib_json/fuzz.h

@@ -0,0 +1,14 @@
+// Copyright 2007-2010 The JsonCpp Authors
+// Distributed under MIT license, or public domain if desired and
+// recognized in your jurisdiction.
+// See file LICENSE for detail or copy at http://jsoncpp.sourceforge.net/LICENSE
+
+#ifndef FUZZ_H_INCLUDED
+#define FUZZ_H_INCLUDED
+
+#include <stddef.h>
+#include <stdint.h>
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size);
+
+#endif // ifndef FUZZ_H_INCLUDED