Bug#878356: cross-gcc-dev should support gcc-8

[Dima Kogan <dima@secretsauce.net>]

Helmut: are you satisfied that this works? The patch set is in-place,
and it applies. There were problems building the packages, and I haven't
looked into that yet.

I don't know how much of these patches you actually use. If you don't
see these failures, then I'm inclined to close this bug. It'd be great
to get everything working, but since you're the only consumer of these,
as far as I know, I'd rather use my limited cycles to fix something
else.

If, however, that IS getting in your way, do tell me, and I'll fix it.