Those 3 system files are normal in 4.8 (and earlier). Note that you might occasionally see two versions of one or two of those, especially after a major Win update -- according to others here, it's quite OK to delete the older version of anything like that.
Slightly off-topic, but closely related ... I too noticed that they're not shown in the chest in v5. Does avast no longer "backup" these files this way, or are they still in the chest but no longer displayed, since many of us were confused to see them there?
(Edit) A second, related question -- is the single screen we now see for the chest the equivalent of the previous "all chest files" screen?