Fix CMake

In Blender project, we have an helper bash script users can use to automatically install and/or compile needed dependencies, and we use CMake tool to build needed libs.

This patch fixes OIIO cmake for linux (note CMakeList.txt was removed from src/, so I just used the one from oiio 1.1.10, which seems to work perfectly).

Thanks for checking it,
Bastien (aka mont29).