Previously I was trying to keep (hoot core-syntax) be just the primitive
syntax, and then redefine everything as part of boot.  But that does
have a downside that we don't have many primitives with which to define
the derived syntax, and also that when we're compiling without the macro
expander we are bloating the compilation unit with needless definitions.

Instead there is a different way, which is to make the expander itself
provide the environment for (hoot core-syntax).  In this way the
definitions stay in one place, which is good for free-identifier=?, and
we don't need to mutate those definitions in place.  For the core
procedures, we also define a module, except there we can swap out their
values using set!.

So, this un-does some work.  On the other hand we define new (hoot
gensym) and (hoot inline-wasm) modules.