I have compiled versions of Rclone for AIX 7.3 and IBM-i 7.4.
They are available here: https://github.com/skytap/rclone
These are delivered as executables due to the complexity of the build.
Additional configuration is required for IBM-i as noted in the readme.
Some functions have been removed.
Good work 
Do you want to upstream any of the code butchery? I'd accept PRs which disabled things on build tags and tested runtime.GOOS to disable features?
I couldn't see the code changes you made in the repo you posted though - might not have looked in the right place!
Thank you. Yes, when I have some time I will get the changes organized and submit them.