`./setup_board --nousepkg --nogetbinpkg` currently fails with a
circular dependency due to pulling in the whole systemd-cryptsetup-udev
dependency chain. This is due to several issue:
* `emerge --root=$ROOT --emptytree` considers ROOT=/ to also be empty,
so it pulls in all host packages. This must've not always been the case.
So we need to pipe the dependency package list through `egrep $ROOT`
to filter only those that would get installed into the desired ROOT
* if SYSROOT=/ and not SYSROOT=ROOT, then virtual/os-headers is missing
from $ROOT package list
* the final filter expression tries to previously looked like this:
(=sys-devel/gcc|sys-devel/binutils-0.9) which also matches
sys-devel/gcc-config and sys-devel/binutils-config, which are
necessary dependencies. Rework the match expression to not filter
those out.
a66bded4ce