message: fix computing sizeof_headers
  Adding 1 to the size of this->data_directories_ and this->sections_ seems to be unnecessary. In this commit, the two '+1' are removed.
diff: @@ -549,8 +549,8 @@ uint32_t Binary::sizeof_headers(void) const {
  size += sizeof(pe64_optional_header);
  }
  - size += sizeof(pe_data_directory) * (this->data_directories_.size() + 1);
  - size += sizeof(pe_section) * (this->sections_.size() + 1);
  + size += sizeof(pe_data_directory) * (this->data_directories_.size());
  + size += sizeof(pe_section) * (this->sections_.size());
  size = static_cast<uint32_t>(LIEF::align(size, this->optional_header().file_alignment()));
  return size;
  