Remove gcc8 platforms
As agreed at PAC on 29th November, this MR drops support for gcc8 in the master
and run2-patches
branches
- @rmatev @clemenci I will not merge this today. I leave it to you if you can check during the weekend, otherwise I do it on Sunday
- @gcorti @kreps @dmuller I'm not sure I have handled the Gauss slots correctly, let's see what happens, some cleanup may be needed
- @sstahl please note that throughput slots will also move to gcc9. Shout if this is not appropriate
- @graven FYI