If brew is installed on Linux, Sagemath thinks this is the primary package manager and, e.g., configure suggests to run brew ... to install new packages. However, linuxbrew is untested as a platform for Sage, and so this is not a good idea.

We change build/bin/sage-guess-package-system so that brew is only tested after the Linux package managers.

We also add a detection for nix-env.

CC: @mkoeppe @collares @jplab

Component: build: configure

Author: Matthias Koeppe

Branch/Commit: u/mkoeppe/prefer_linux_package_manager_over_linuxbrew @ 9af33a1

Issue created by migration from https://trac.sagemath.org/ticket/32753