Maintain Haiku support

It was pointed out that the 2.10 release notes are pushing to drop Haiku support.  The qemu port is currently working as-is under Haiku.

Was there a reason this was recommended? Is there anything Haiku can do to keep it from being dropped?

We're working on a docker container to cross-compile rust-lang for Haiku, could this be of some use to qemu when complete?