[Dev] do we need the [kernels], [cross], and [unmaintained] repos anymore?

[bill-auger]

i see also there are some PKGBUILDs in [unmaintained] that are
also not built - and the built packages in [unmaintained] have
no PKGBUILDs

i think we should clean them up - the repo-lint report includes
warnings treats about packages without a PKGBUILD, or PKGBUILDs
without a built package - we dont pay much attention to that; but
it would be great if someday there were no warnings on it

maybe we could put things like that in [unmaintained] - maybe
even change its name to [~/unmaintained] so that the repo-linter
would ignore them as "experimantal"