New `#%app/no-return` and `#%app/value` functions at the Chez Scheme
level allow schemify to communicate that function calls will not
return or will return a single value. The schmeify pass may have this
information because a Racket-level primitive is declared that way
(such as `error` or `raise-argument-error` for no-return, or most
functions for single-valued) or because single-valuedness is inferred.
There's currently no inference for no-return functions, because those
are relatively rare. An `#%app/value` is used by schemify only for
imported, non-inlined functions, since cp0 can already deal with local
functions and primitives.
There's a start here at adapting the "optimize.rktl" test suite for CS
--- and that effort triggered these improvements plus some other
low-hanging fruit. But a lot more is needed to adapt "optimize.rktl"
and to make some additional optimizations happen.
This commit merges changes that were developed in the "racket7" repo.
See that repo (which is no longer modified) for a more fine-grained
change history.
The commit includes experimental support for running Racket on Chez
Scheme, but that "CS" variant is not built by default.
