Add a libfuzzer for usrsctp, an SCTP userland stack.

testing/libfuzzer/fuzzers/usrsctp_fuzzer.cc

+// Copyright 2016 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 "third_party/usrsctp/usrsctplib/usrsctplib/usrsctp.h"
+
+static int ignore1(void* addr,
+                   void* data,
+                   size_t length,
+                   uint8_t tos,
+                   uint8_t set_df) {
+  return 0;
+};
+
+static void ignore2(const char* format, ...) {};
+
+struct Environment {
+  Environment() {
+    usrsctp_init(0, ignore1, ignore2);
+  }
+};
+
+Environment* env = new Environment();
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
+  usrsctp_conninput(nullptr, data, size, 0);
+  return 0;
+}