setup: built-in tar

[DJ Delorie]

> Yes, however, they should be in the same directory.  Preferably just
> shipping them along with the install is preferable.  Keeping some old
> set of sources around is just a pain.

Last time I talked about this with RMS, the result was that the
minimum requirements be that it be on the same "site" (meaning same
machine or cluster and same protocol (ftp/http)) and available to the
user at the time the user downloaded the binary.  I assume its
location can't be obscured.

Beyond that is merely convenience.

We don't need to keep sources around on FTP in case some user who
FTP'd a binary less than three years ago suddenly decides they need
the sources.  That rule only applies to a 3b distribution; our ftp is
3a.