Add initial libfuzzers for fm2js transpiling and XML parsing.

testing/libfuzzer/unittest_main.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.
+
+// A simple unit-test style driver for libfuzzer tests.
+// Usage: <fuzzer_test> <file>...
+
+#include <fstream>
+#include <iostream>
+#include <iterator>
+#include <vector>
+
+// Libfuzzer API.
+extern "C" {
+// User function.
+int LLVMFuzzerTestOneInput(const unsigned char* data, size_t size);
+// Initialization function.
+__attribute__((weak)) int LLVMFuzzerInitialize(int* argc, char*** argv);
+}
+
+std::vector<char> readFile(std::string path) {
+  std::ifstream in(path);
+  return std::vector<char>((std::istreambuf_iterator<char>(in)),
+                           std::istreambuf_iterator<char>());
+}
+
+int main(int argc, char** argv) {
+  if (argc == 1) {
+    std::cerr << "Usage: " << argv[0] << " <file>..." << std::endl;
+    exit(1);
+  }
+
+  if (LLVMFuzzerInitialize)
+    LLVMFuzzerInitialize(&argc, &argv);
+
+  for (int i = 1; i < argc; ++i) {
+    std::cout << argv[i] << std::endl;
+    auto v = readFile(argv[i]);
+    LLVMFuzzerTestOneInput((const unsigned char*)v.data(), v.size());
+  }
+}