Blender Git Loki

install_deps: update some libs, and various improvements/fixes.

This commits:
- Updates some libraries to latest officially supported versions:
** Numpy: 1.17.5
** OCIO: 1.1.1
** OIIO: 2.1.15
** OSL: 1.10.10
** OIDN: 1.2.1

- Re-enables some distro packages (like OSL, OIIO, OCIO...).

- Add missing 'CMake cleanup commands' for generated CMake update
command, for Embree, OIDN and OpenXR.

- Generalizes using min/max versions of accepted libraries, if no
package can be found in specified range then it is built from sources.

The later point should help keeping things a bit in better conditions,
although current maximal accepted versions are somewhat arbitrary guess
currently.