preparing for GCC 9

[Matthias Klose <doko@debian.org>]

Hi,

stage3 is approaching for GCC 9 development, and I put together a first gcc-9
package.  I won't upload that to experimental yet because sonames and package
names will still change, and gcc-for-host will add a few hundred binary packages
as well.  So please test/check these in an Ubuntu cosmic chroot. Found at

  https://launchpad.net/~doko/+archive/ubuntu/toolchain/

Some things which need some work:

 - Ada is currently disabled. Some patches need updates, I didn't
   spend time on these.  Also please forward patches which can be
   applied upstream.  Syq, Nicolas, any update would be appreciated.

 - gdc is disabled, will be finally merged upstream. I'll re-enable
   that in a follow-up snapshot.

 - Building of the cross compiler packages is not yet started.

 - The gcc-for-host patches should be updated. With the freeze
   approaching, I don't want to integrate these into 8 anymore.
   Helmut, an update would be appreciated.

Finally I gave up converting the VCS history, and started from scratch with new
git VCS repos.  Found at https://salsa.debian.org/toolchain-team/

Matthias