Make code more readable. No functional changes

Requires :
https://gitlab.alpinelinux.org/tmhoang/mkinitfs/-/merge_requests/1

Thre are a couple of problems with the mips kernels:
- linux-octeon does not have initramfs
- System.map has different name (upstream problem)

Those issues needs to be solved before we can ship netboot support for
mips64.

we hardened the read permissions in 27b8dc5b (main/mkinitfs: fix
permissions of initramfs) this broke netboot.

ref #11071

there are no linux-lts kernel for armhf

also add doas to extended image

Olliver Schinagl authored 6 years ago and Natanael Copa committed 6 years ago

Signed-off-by: Olliver Schinagl <oliver@schinagl.nl>

create a symlink to latest netboot release. This is to make it easy to
create urls without version numbers like:
http://dl-cdn.alpinelinux.org/alpine/latest-release/releases/x86_64/netboot