In slackware-current, on April 8 libva was updated to version 1.8.0, but libva-intel-driver (aka intel-vaapi-driver) was updated only to version 1.7.3, even though both were then at version 1.8.0.
This has probably arisen because libva-intel-driver has changed its name to intel-vaapi-driver and its repository is at
https://github.com/01org/intel-vaapi-driver . Both libva and intel-vaapi-driver are now at version 1.8.1.
