Two patches.  We need a newer version of openimageio to update to the
newest Blender LTS version.  However the newer version of openimageio
doesn't work with our old version of openshadinglanguage... for now,
I've just preserved an older version of openimageio for
openshadinglanguage to use.

It would be ideal to update openshadinglanguage and add that as an input
to Blender too since that would open up custom shading nodes for our
Blender users, but alas, I ran into trouble upgrading
openshadinglanguage and don't have time to do that right now.
I suggest we get in the Blender update and if someone wants to take a
crack at upgrading OSL and adding to Blender too they can do that as a
future patch series.

 - Christine