Revert "[build] Rewrite guile-func-name-check in Scheme, adding features."

Revert "[build] Rewrite guile-func-name-check in Scheme, adding features."

This reverts commit 6832604efa0f175a70be700624c365547fb27878. Not only
does this fail on a fresh build due to a lack of "guile", but even if it
did have its Makefile fixed, it would take too long to run, because the
rest of Guile isn't compiled.

The right thing is to avoid invoking Guile until after at least psyntax
and boot-9 have been compiled.

This commit can be reinstated if we move doc snarfing to a phase that
happens after module/ is compiled.