We also need to save C ABI volatile registers before calling the signal handler in order to be able to reliably resume. Add signal-handler and leaf-signal-handler subprimitives to preserve volatile registers before invoking the signal handler C function.
- change some primitives into sub-primitives: fixnum+ fixnum- fixnum* inline-cache-miss inline-cache-miss-tail
- rename some relocation types for clarity
- some other minor re-organizations and cleanups
Non-optimizing compiler now special-cases dip, 2dip, 3dip following a
literal quotation: this allows us to break the dip/slip meta-circle
without explicit calls to >r/r>