Add a fuzzer for flatbuffers, derived from the one used in Chromium:

https://code.google.com/p/chromium/codesearch#chromium/src/testing/libfuzzer/fuzzers/flatbuffers_verifier_fuzzer.cc

(mirrored from cl 122676317)

Change-Id: I0074af435cf37f5e6368b040563c3733d9e02345

tests/fuzzer/flatbuffers_verifier_fuzzer.cc

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+#include <stddef.h>
+#include <stdint.h>
+#include <string>
+
+#include "third_party/flatbuffers/tests/monster_test_generated.h"
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
+  flatbuffers::Verifier verifier(data, size);
+  MyGame::Example::VerifyMonsterBuffer(verifier);
+  return 0;
+}