Alas, nproc isn't portable (sched_getaffinity() syscall) and
scripts/portability.sh already has two fallbacks (sysctl -n hw.nproc for
mac/bsd and if that doesn't work either it sets CPUS=1).
With this, I built on mac outside of homebrew, albeit cheating to get .config:
$ homebrew
$ make macos_defconfig
$ make clean
$ exit
$ scripts/prereq/build.sh #ignoring SO many warnings
$ mkdir prereq; mv toybox-prereq prereq/
$ for i in $(prereq/toybox-prereq); do ln -s toybox-prereq prereq/$i; done
$ PATH=$PWD/prereq:$PATH scripts/make.sh
$ ./toybox
6 files changed
