[objc] Show macos-[modern|full|system] platforms when displaying help. Fix #534 (#619)
[objc] Show macos-[modern|full|system] platforms when displaying help. Fix #534 (#619)

Fixes https://github.com/mono/Embeddinator-4000/issues/534
jonathanpeppers/Embeddinator-4000,mono/Embeddinator-4000,mono/Embeddinator-4000,mono/Embeddinator-4000,jonathanpeppers/Embeddinator-4000,jonathanpeppers/Embeddinator-4000,jonathanpeppers/Embeddinator-4000,mono/Embeddinator-4000,jonathanpeppers/Embeddinator-4000,jonathanpeppers/Embeddinator-4000,mono/Embeddinator-4000,mono/Embeddinator-4000,jonathanpeppers/Embeddinator-4000,mono/Embeddinator-4000