rpm-4.13 stopped bringing alt-gpgkeys in, and specifying it
explicitly for STAGE1_PACKAGES didn't help somehow; don't presume
/usr/lib/alt-gpgkeys/ existence anyways.

Installation finishes just fine if bzip2-compressed
hash files are removed *but* apt-cdrom add will fail.

Just a hook to export alt-gpgkeys pubring data.

We've got some parts of it in build-distro feature,
and some went to dev feature for no real reason.

But a bare installer might go without package base,
and LiveCDs other than live-builder might find local
repository useful given aufs2 root overlay.

Now the overall scheme is more straightforward:
- a distro:
  + asks that a package repo be included
  + cares to further add the packages to it
- a repo feature:
  + pulls in sub/main for it to happen
  + provides genbasedir script to create repo metadata
  + supplements live feature with repo configuration