yum+mock patches for cross-compile and intro

[Ken MacLeod]

I've been working on adding support for cross-compiling to yum, mock,
and up until now, plague.  I only recently saw the new discussion on
fedora-devel.

I'm in the Fedora->XXXX group for now, I want to use Fedora
infrastructure with other's cross-compilers and RPMs, then add our
own.  Upstream spec files would remain unchanged, I think we've only
ever changed one outside of "taking over the kernel".  Our internal
coding guidelines require GNU auto-tools so our spec files are simple
and shared for all cross tools and targets.

Our primary cross targets are using Wind River and MontaVista Linux,
ppc and x86, over multiple releases.  We also use TimeSys as an
up-to-date reference target (ie. TimeSys is our "Fedora") and native
RHEL3, 4, and 5 targets (both our x86 Fedora->blades and internal
systems).

I'd like to use Koji/Bodhi/mash/pungi as our internal build system
where we submit one of our packages and have it build for all targets
and target releases, and we build release ISOs from all of those.

I've posted my most recent snapshot patches to yum-devel and
fedora-buildsys for reference but the yum patch is against CentOS4 yum
2.4.3 for our current RHEL4 build system and I haven't had a chance to
update the mock patch to current CVS.  It looks like we'll need to go
to F7 to use the whole suite of tools, so look for updates to be
against current revs.  The mock patches include configs for and were
tested with DENX ELDK so folks could use them without registering or
needing evaluation licenses.

  https://lists.dulug.duke.edu/pipermail/yum-devel/2007-June/003849.html
  https://www.redhat.com/archives/fedora-buildsys-list/2007-June/msg00041.html

I'm still re-reading the recent discussion before I add anything
there.  It looks like a key point was identifying the split between
Fedora->Fedora and Fedora->XXXX.

  -- Ken