This only requires minor changes to the Solus .eopkg patchset. However, it also requires the changes in PR72 for solus-sc.
The (unused) _len parameter was removed from a lot of the API in appstream-glib 0.5.0
I replaced the original patch from @saintdev (v 0.6.8) with a newer one (v 0.6.11) since it wasn't added to the repo yet