[gentoo-dev] Setting USE_EXPAND defaults in profiles (in some cases)

[Donnie Berkholz]

For ebuilds that use USE_EXPAND to pull in other dependencies rather
than just internally building drivers (I suspect xorg is the only one),
I've been thinking of a way to make the whole setup cleaner.

agaffney suggested this in the first place, and every time I think about
it, it seems like a better idea. If we set VIDEO_CARDS and INPUT_DEVICES
in the arch profiles, we get the arch-specific defaults we need without
the really hugely ugly indecipherable mess in the ebuilds that nobody
can understand besides Josh_B and me. The very strange corner case this
doesn't work with is if people manually set VIDEO_CARDS="", then they
will no longer get the behavior of pulling in everything. But the
default case will still work great.

I'm going to go ahead with this in the next week or so unless I hear
massive objections.

Thanks,
Donnie