@Alex-Gardner Ok, thanks much for running that. Since it built clean for you, that made it clear that there was something bad about my environment (the whole reason I'm down this rabbit hole!).
Anyway, my typical configuration is to ssh into my Linux machine from a W10 box using Cygwin/SSH. Apparently something in the build.sh script doesn't like that; hence my failures. When I build directly through the console of that Linux machine the build completes successfully.
Sorry for the confusion, and thanks to all for the responses.