devel/plan9port: unbreak, update, and undeprecate the port (+)
- Fix the conflict with badly named kcmp(2) syscall introduced in recent FreeBSD-CURRENT/14.1
- Update to the latest GitHub commit, shorten the GH_TAGNAME, and merge two installation targets into one (which still begs for a further pre/post-stage separation and cleanup)
Fixes: d846b489087a
PR: 278145