pkgsrc on alpine linux (non-gnu userland) - trip report

[nia <nia%NetBSD.org@localhost>]

recently set up an alpine linux in nvmm for cross compiling compilers for
netbsd/amd64. decided to test pkgsrc on it.

bootstrapping is fine (hooray).

installing packages revealed problems.

- platform tools for linux expects /bin/bash. there's no such thing.
  making that conditional helped.

- then, there's a dependency loop on flex as a dependency for bison
  as a dependency for bash. i just installed bison from alpine packages,
  that helped. i suspect not having flex violates long held expectations
  so i won't demand that be fixed.

- xz from busybox isn't good enough to build gettext-tools.
  it needs -5, xz from busybox doesn't have -5.
  TOOLS_PLATFORM.xz=/usr/pkg/bin/xz in mk.conf helped.

- i was able to build rust-bin because it explicitly uses
  the musl bins if glibc isn't detected. lang/rust should
  probably do the same.

since linux userlands are far from predictable these days,
it might make sense to only define tools for linux that
are actually in POSIX, unless we can actually detect busybox etc.

thoughts?