The Google polyglot build tool at https://bazel.build/ turned out to be a bit more trouble to port than usual, but it is somewhat functional with the preliminary port below.
The effort is losely based on the previous attempt by Matt Hildebrand from 2020 (thanks Matt!). I'm not yet sure if I want this in the tree. I'll keep it around until somebody else wants to put it in. I still haven't figured out how to configure the packaged bazel to rebuild bazel from the source tree. The toolchain mechanism is just too much for me to grasp. If somebody figures out the magic, do let me know. Thanks Greg
bazel.tgz
Description: Binary data