The issue is that use/fonts/infinality doesn't actually
require the script hook thus registering the feature's
name in FEATURES variable so that the feature's contents
get copied over is not neccessary (distcfg.mk build-up
will have happened anyways).

But that's confusing if one's forgot this peculiarity
(like me today) or never knew of it, so let's spare
some frustration.

This feature should be more generally applicable indeed.

These have been proofread somewhat to correspond
to the current state of affairs; a missing one
was added for fonts feature.

Thanks cow@ for both the packages and suggestion.

This includes an updated version of 50-fontconfig script
which actually works (the preliminary one attached to #28612
didn't); thanks zerg@ and cow@ for providing the incentive
to introduce it.

Based on m-p-d and installer-feature-kdesktop-fontconfig.