Drop support for GCC < 8 in Sage 9.8

[mkoeppe]

(see #32074)

Depends on #33062

CC: @dimpase

Component: build: configure

Author: Matthias Koeppe

Branch: 27a0882

Reviewer: Dima Pasechnik

Issue created by migration from https://trac.sagemath.org/ticket/34266

[mkoeppe]

Dependencies: #32074

[mkoeppe]

Changed dependencies from #32074 to #32074, #33062

[mkoeppe]

Branch: u/mkoeppe/drop_support_for_gcc___8_in_sage_9_8

[mkoeppe]

Last 10 new commits:

f2b52ef	.github/workflows/ci-linux.yml: First run all 'standard' jobs, then 'minimal', ...
ca6d163	.github/workflows/ci-linux.yml: Rename stages
5713937	sage -package list --has-file, --no-file: Handle disjunctions
8c7e0c4	Merge #33062
4e8ec60	.github/workflows/docker.yml: Remove debian-stretch, fedora-{26,27,27}
a9f4b15	tox.ini (gcc_8), build/pkgs/_gcc8: New
120ab05	tox.ini (envlist): Replace docker-ubuntu-trusty-minimal with docker-ubuntu-trusty-toolchain-gcc_9-minimal
9b38bad	build/pkgs/_gcc{9,10,11}/distros/opensuse.txt: New
ccce5b1	.github/workflows/docker.yml: Use gcc_8 with ubuntu-bionic, linuxmint-19.x
27a0882	.github/workflows/docker.yml: Use gcc_11 with opensuse-15.{3,4}

[mkoeppe]

Author: Matthias Koeppe

[mkoeppe]

Commit: 27a0882

[dimpase]

comment:5

why is #32074 (a meta-ticket) listed as a dependency here?

[mkoeppe]

comment:6

So that it doesn't get accidentally merged into Sage 9.7

[mkoeppe]

comment:7

Let's get this in please

[mkoeppe]

Changed dependencies from #32074, #33062 to #33062

[dimpase]

comment:8

what's happening to workflow/tox-* ? why is it being removed?

[mkoeppe]

comment:9

These tests have been merged into ci-linux.yml (actually done in #33062)

[dimpase]

comment:10

OK

[dimpase]

Reviewer: Dima Pasechnik