rc: switch to 9fronts source

[hovercats]

as discussed on irc, I switched our rc to a repo similar to upstream 9front. there were couple patches missing in this repo, which existed in 9front, so I pulled in those.

I took the liberty and fixed a warning about mains return type, as plan 9 returns a string, and not an int.

I omited the first existing patch, because the sources were too different for me to easily port over.

if you feel different about the patches here, feel free to fix it when merging, or send them to me, and ill add them to the pr.