[dvipdfmx] writing an uncompress stream

[Ulrike Fischer]

> I think dvipdfmx doesn't compress stream objects having /Type /Metadata.
> See, the following ChangeLog entry.

> 2016-06-25  Shunsaku Hirata  <shunsaku.hirata74 at gmail.com>

>         Modify to make PDF/A generation a bit easier.
>         * pdfobj.c: Do not compress XMP Metadata.

Oh how nice. It seems to work, but in a few case my editor seems to 
get confused about the encoding and shows something that looks 
compressed.

> If adding a new option to control compression behavior is still
> preferred, please let me know. Implementation itself is quite easy.

No, that it perfect. Getting this automatically is fine. 

I wonder if one can port this to pdftex. 

Thanks. 

Ulrike