This experimental target has no recent active maintainer. It's the only
linker backend complaining about this branch and I can't make sense of
the stack trace.
This can be fixed asynchronously by anyone who wants to maintain plan9
support. It does not need to block this branch.
The self-hosted aarch64 backend is not currently functional due to the
Liveness changes. A previous commit disabled aarch64 on the behavior
tests; this commit disables it and arm for the test cases. Moreover, all
incremental test cases have been unified into shared cross-platform
cases, which can be gradually enabled as the backends improve.