So, second notice / heads up on this. Plan is:
to roll back to libgcc / gcc 7.4.x on 10.4, 10.5, and maybe on i386 10.6. to conflicts_build every clang version >= 5.0 when build_arch is i386 on every gcc version >= 5. and then this will perhaps stay like this forever, or at least until some solution comes along to the libgcc / i386 building issues. I assume anyone who cares already knows all the details, but feel free to ask if you have any questions or have the insight to come up with any solutions. Bet, Ken