Log Message:
libplacebo: Import libplacebo-6.338.1 as multimedia/libplacebo

libplacebo is, in a nutshell, the core rendering algorithms and ideas
of mpv rewritten as an independent library. As of today, libplacebo
contains a large assortment of video processing shaders, focusing on
both quality and performance.

Packaged in pkgsrc-wip by <leot> and <wiz>.

This will be needed for multimedia/mpv.