Blender Git Loki

Update install_deps.sh for ArchLinux.

The script is updated for ArchLinux, since all dependencies are included in Arch's official repositories.

I've made a few changes, such as enabling OCIO and OSD without requiring locally installed lib-path, and a fix to ''get_package_version_ARCH()' so it ignores package epoch (as in the case of ffmpeg).

I intend to look at OpenVDB next.

Reviewers: mont29

Differential Revision: https://developer.blender.org/D1901