wip/chezscheme-racket 9.5.9.8 NetBSD

Chez Scheme is both a programming language and an implementation of that language, with supporting tools and documentation. This variant of Chez Scheme is extended to support the implementation of [Racket](https://racket-lang.org/).

Major additions to Chez Scheme in the Racket variant:

* AArch64 support

* pb (Portable bytecode) support, which is mainly useful for bootstrapping a build on any supported platform

* Unboxed floating-point arithmetic and flvectors

* Type reconstruction during optimization (especially for safe code)

* Continuation attachments

* Parallel garbage collection, in-place garbage collection for old-generation objects (instead of always copying), and reachability-based memory accounting

* Ordered finalization, immobile (but collectable) objects, and weak/ephemeron generic hash tables