After --all-variants, --verify-packs printed "hashes checked during the
build" for the platform-only, truth and required-only packs and compared
none of them, so one missing a file its narrowed list requires passed.
Each pack is now held to the platform list narrowed the way it was built:
source and required_only, read from its name, reach the baseline, the
region grouping and the replay of the core extras.
The pack integrity check rebuilt the core extras with no taken paths and
tested presence alone, so it credited core files at paths the platform's
own file holds and printed a core count the builder contradicted. It now
replays the builder's placement through packextras.hidden_extras and
compares each placed member with the copy the builder resolves.
Abdessamad Derraz