Memory leak in subprocess when 'environment' argument is provided.

  // Like above, we need to construct the environment that we'll pass
  // to 'os::execvpe' as it might not be async-safe to perform the
  // memory allocations.
  char** envp = os::raw::environment();

  if (environment.isSome()) {
    // NOTE: We add 1 to the size for a NULL terminator.
    envp = new char*[environment.get().size() + 1];

    size_t index = 0;
    foreachpair (const string& key, const string& value, environment.get()) {
      string entry = key + "=" + value;
      envp[index] = new char[entry.size() + 1];
      strncpy(envp[index], entry.c_str(), entry.size() + 1);
      ++index;
    }

    envp[index] = NULL;
  }

  ...

  // Need to delete 'envp' if we had environment variables passed to
  // us and we needed to allocate the space.
  if (environment.isSome()) {
    CHECK_NE(os::raw::environment(), envp);
    delete[] envp; // XXX Does not delete the sub arrays.
  }