Hello Org!

I attached a patch that is required to get ox-odt to work on
guix/nix/other distributions where package files are placed in a
read-only directory.  After the file styles.xml is copied to /tmp, now
we set read-write permissions to it before trying to write it.  Before
this patch, we got the error:

  'OpenDocument export failed: Buffer is read-only: #<killed buffer>'.

It's my first patch and is just 1 line long, so following instructions
on https://orgmode.org/worg/org-contribute.html#commit-messages I added
the TINYCHANGE cookie.  Tests (make test) are passing.

Thanks!
Nicolò