Error boostraping: list-dependencies: nawk not found

[klu <kludev%gmail.com@localhost>]

I'm trying to bookstrap pkgsrc on vanilla alpine linux. Bootstrap
failed quite early on on making some of the `pkgtools`. E.g.,
`cwrappers`, e.g.:

```
===> running: (cd /root/pkgsrc/pkgtools/cwrappers &&
/root/pkgsrc/bootstrap/work/bin/bmake  MAKE_JOBS=3
PKG_COMPRESSION=none PKGSRC_KEEP_BIN_PKGS=no
MAKECONF=/root/pkgsrc/bootstrap/work/mk.conf install)
/root/pkgsrc/mk/pkgformat/pkg/list-dependencies: line 47:
/usr/pkg/bin/nawk: not found
```

I also tried bookstrap without cwrappers: `./bootstrap --cwrappers
no`. It failed at making the next `pkgtool` package (I don't remember
which), with a similar error above.

Here's the full log: https://envs.sh/FIp.txt

Any idea what went wrong? Thanks!