make fetch-list

[Joerg Sonnenberger <joerg%britannica.bec.de@localhost>]

Hi all,
earlier today I have added the support for depends-fetch and
depends-checksum. They are intended to replace most of the current uses
of the "make fetch-list | sh" idiom and fix some issues with the latter.
E.g. mirrors with bad files are handled gracefully if FAILOVER_FETCH is
set.

This brings me to the more interesting question of how "make fetch-list"
should behave. I think the current logic is too complicated for the
purpose of "running on a second machine without pkgsrc" and if you
already have pkgsrc, you can use depends-fetch/depends-checksum anyway.
So if you are using this target in that way or have a third (or fourth)
way, I'd like to know how.

Joerg