Remove the dependency from set-base to set-devel, making the two sets
orthogonal. This means base is now "the complete base system without
compilers".
The use case for this is users who want to install the entire runtime
system so that they don't have to worry about whether something is
installed or not, but who don't want compilers installed, which is
common for containers or jails, and for organisations with a policy
of not installing compilers on production systems.
set-base is already not the complete base system (because it doesn't
include tests, lib32, or debug symbols), so this is less of a semantic
change than it might appear. It is a departure from how dist sets work,
but other systems (e.g., NetBSD) already separate compilers from the
base set.
Update the language in bsdinstall, and ensure set-devel is staged on the
release media in pkgbase-stage.lua, since set-base no longer implies it.