Move SPARC over to slimmed-down EMIT-ERROR-BREAK interface, part 2.
* Now that the noisy touch-lots-of-files work has been done, we
can settle in to do the harder-to-validate bits that are entirely
contained within a single file.
* Based somewhat on the PPC version in 22.214.171.124, with a
slightly different choice of implementation strategy, and a result
that hews closer to the code originally replaced.