This adds the possibility to parse /proc/consoles to find a primary console.
Then, on AArch64 this is used in the installation image. On AArch64, the boot
usually happens with chosen device tree that contains the serial console.
On x86_64, this does not happen so often, so we keep the installation iso
minimal there.
The primary console is chosen, but there is a fallback to any non-virtual one.
Virtual console (/dev/tty0) is skipped, because that one can point to any
console, like /dev/tty1 and so on. So it's not safe to register agetty on it.
* gnu/build/linux-boot.scm (read-linux-consoles): New variable.
* gnu/services/base.scm (default-serial-console): Use primary console as
fallback.
* gnu/system/install.scm (%installation-services): Add agetty tty for
consoles.
Change-Id: Iae01f7bc85b5ffdef2e52b1d0710889915b0f54a
Signed-off-by: Rutherther <rutherther@ditigal.xyz>