Without binary repo: dtbtool doesn't get built for as dependency for linux packages

Created by: ollieparanoid

How to reproduce:

# delete all packages
pmbootstrap zap -p

# build a kernel depending on dtbtool without binary repo enabled
pmbootstrap --mirror-pmOS="" build linux-amazon-thor

# => pmbootstrap only builds dtbtool for armhf,
#    but abuild tries to install it for x86_64 in the native chroot

Workaround:

pmbootstrap --mirror-pmOS="" build dtbtool
pmbootstrap --mirror-pmOS="" build linux-amazon-thor