message: add missing symbol to `gcs_filesystem`
diff: @@ -1249,6 +1249,11 @@ void ProvideFilesystemSupportFor(TF_FilesystemPluginOps* ops, const char* uri) {
  ops->writable_file_ops = static_cast<TF_WritableFileOps*>(
  plugin_memory_allocate(TF_WRITABLE_FILE_OPS_SIZE));
  ops->writable_file_ops->cleanup = tf_writable_file::Cleanup;
  + ops->writable_file_ops->append = tf_writable_file::Append;
  + ops->writable_file_ops->tell = tf_writable_file::Tell;
  + ops->writable_file_ops->flush = tf_writable_file::Flush;
  + ops->writable_file_ops->sync = tf_writable_file::Sync;
  + ops->writable_file_ops->close = tf_writable_file::Close;
  ops->read_only_memory_region_ops = static_cast<TF_ReadOnlyMemoryRegionOps*>(
  plugin_memory_allocate(TF_READ_ONLY_MEMORY_REGION_OPS_SIZE));
  