mac-universal build target

[ninjamuffin99]

Been testing and using the new arm64 version of lime very nicely! It's possible to compile downwards to x86 from apple silicon, but then creating a universal binary would involve running all of the build/compile commands twice, and then combining the builds with lipo.

A good convenience might be something like a mac-universal target, which would compile both x86 and arm for mac, and then run lipo to create a universal binary with no fuss. Of course it might be unpleasant for day to day use, but rather something nice for when getting ready to package something up!