* Use a generation number for the bindist tarballs, with compatibility
symlink. Eventually we'll use this to avoid building in a "stale"
chroot (i.e. populated by old world).
* Don't bother running ldconfig on i386, it is evidently not needed since
the other arches work fine without it
* Don't require the script to be called from inside the branch directory;
follow standard practise and pass the branch to build as an argument.
* Populate the chroot with the BSD.local.dist mtree file
* Add whitespace for readability, and sprinkle liberally with comments
* Comment on some inscrutable parts of the script which were presumably
put there to work around a (perceived) problem, but which I can't
understand.
