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
