message: Update protobuf.gyp to support v3.19.3.
diff: '<(protobuf_cpp_root)/any.cc',
  '<(protobuf_cpp_root)/any_lite.cc',
  '<(protobuf_cpp_root)/arena.cc',
  + '<(protobuf_cpp_root)/arenastring.cc',
  '<(protobuf_cpp_root)/compiler/importer.cc',
  '<(protobuf_cpp_root)/compiler/parser.cc',
  '<(protobuf_cpp_root)/descriptor.cc',
  '<(protobuf_cpp_root)/io/zero_copy_stream.cc',
  '<(protobuf_cpp_root)/io/zero_copy_stream_impl.cc',
  '<(protobuf_cpp_root)/io/zero_copy_stream_impl_lite.cc',
  + '<(protobuf_cpp_root)/map.cc',
  '<(protobuf_cpp_root)/map_field.cc',
  '<(protobuf_cpp_root)/message.cc',
  '<(protobuf_cpp_root)/message_lite.cc',
  '<(protobuf_cpp_root)/parse_context.cc',
  '<(protobuf_cpp_root)/reflection_ops.cc',
  '<(protobuf_cpp_root)/repeated_field.cc',
  + '<(protobuf_cpp_root)/repeated_ptr_field.cc',
  '<(protobuf_cpp_root)/service.cc',
  '<(protobuf_cpp_root)/stubs/common.cc',
  '<(protobuf_cpp_root)/stubs/int128.cc',
  '<(protobuf_cpp_root)/any.cc',
  '<(protobuf_cpp_root)/any_lite.cc',
  '<(protobuf_cpp_root)/arena.cc',
  + '<(protobuf_cpp_root)/arenastring.cc',
  '<(protobuf_cpp_root)/compiler/code_generator.cc',
  '<(protobuf_cpp_root)/compiler/command_line_interface.cc',
  '<(protobuf_cpp_root)/compiler/cpp/cpp_enum.cc',
  '<(protobuf_cpp_root)/compiler/cpp/cpp_message.cc',
  '<(protobuf_cpp_root)/compiler/cpp/cpp_message_field.cc',
  '<(protobuf_cpp_root)/compiler/cpp/cpp_padding_optimizer.cc',
  + '<(protobuf_cpp_root)/compiler/cpp/cpp_parse_function_generator.cc',
  '<(protobuf_cpp_root)/compiler/cpp/cpp_primitive_field.cc',
  '<(protobuf_cpp_root)/compiler/cpp/cpp_service.cc',
  '<(protobuf_cpp_root)/compiler/cpp/cpp_string_field.cc',
  '<(protobuf_cpp_root)/compiler/subprocess.cc',
  '<(protobuf_cpp_root)/compiler/zip_writer.cc',
  '<(protobuf_cpp_root)/io/strtod.cc',
  + '<(protobuf_cpp_root)/map.cc',
  '<(protobuf_cpp_root)/map_field.cc',
  'custom_protoc_main.cc',
  ],
  