Package libplacebo5 for vlc to unblock rest of the distro
As far as I understand, currently vlc is the only blocker for libplacebo 6. We can package libplacebo5 for that and update libplacebo to 6 for the rest of distro. As vlc is already using ffmpeg4.4, this shouldn't cause any issues.
Arch being on an old libplacebo version has become more annoying after ffmpeg@a053989c, since one now can't use a newer libplacebo without a custom build of ffmpeg.
Edited by Baicheng Liu