Add compatibility checks for fancy parts of the demos

Dependencies

• [2] ZSVCCJBX Fixes for CI
• [3] BH5XPS7C Add 07-vm-integration test
• [4] BP57Q2OG Split up flake
• [5] QSIJOFRU Tweak 03
• [*] EGQ4SEV5 Add demo for 04
• [*] ZFMPQAFV Fix and extend cross compilation with static builds
• [*] VUARRVTI Clean up strings
• [*] TEQJC3HX Add 03-nix-container

Change contents

• edit in 07-vm-integration-test/demo.sh at line 29
  [3.5696]

  [3.5696]
  + # https://github.com/NixOS/nixpkgs/issues/124371

  + if [ "$(stat -c '%a' /dev/kvm)" != 666 ]; then

  + n "If /dev/kvm is not world-read-writable VMs will be emulated which is prohibitively slow!"

  + fi

  +
• edit in 04-cmake-and-cross/demo.sh at line 50
  [8.1419]

  [8.1419]
  +

  + if [ ! -e /proc/sys/fs/binfmt_misc/aarch64-linux ] || ! grep -q enabled /proc/sys/fs/binfmt_misc/aarch64-linux; then

  + n "It seems aarch64-linux binfmt emulation is not available, the following part of the demo may not work"

  + fi
• edit in 04-cmake-and-cross/demo.sh at line 61
  [9.2414]

  [7.1980]
  + ,

  + , " boot.binfmt.emulatedSystems = [ \"aarch64-linux\" ];"
• edit in 03-nix-container/podman-setup-script.nix at line 27
  [4.1723]→[4.12:65](∅→∅),[4.65]→[2.287:437](∅→∅)
  − fi

  −

  − if ! grep -q "^''${USER}:" /etc/subuid; then

  − >&2 echo "No subuid range defined for user, consider running 'sudo usermod --add-subuids 10000-75535 ''${USER}' to allow rootless podman to work"
• edit in 03-nix-container/demo.sh at line 20
  [10.5627]

  [10.5627]
  +

  + if ! grep -q "^${USER}:" /etc/subuid; then

  + n "No subuid range defined for user, consider running 'sudo usermod --add-subuids 10000-75535 ${USER}' to allow rootless podman to work"

  + fi