[Libosinfo] [osinfo-db][Patch] Add variant-id + virtual and xen extension

[Fabiano Fidêncio]

[snip]
Reviewed-by: Fabiano Fidêncio <fidencio at redhat.com>

And also pushed already together with the tests part for libosinfo.

Thanks for the contribution!

(And only now I've noticed that 4 days ago I've replied this just to
the sender and not for the list :-/)