mfulc_des_brute added the Homebrew openssl@3.6 include directory, which
the macOS runners no longer have, and -Wmissing-include-dirs under
-Werror stopped the build. It now uses brew --prefix openssl, as #3734
did for mfd_aes_brute.
Since MSYS2 filesystem 2026.10.18 /etc/profile runs post-install
scripts on the first start only, so ProxSpace never installed its
packages and the build found no arm-none-eabi-gcc. The workflow now
runs ProxSpace's setup script when setup\installed is missing.
The third mfulc_des_brute test in pm3_tests.sh is now labelled 3/3.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>