[R6RS] Does for-each tail-call on last element?

[dyb at cs.indiana.edu]

> Subject basically says it.  Should `for-each' be specified to perform
> a tail call on the procedure when it reaches the last element(s)?  (We
> do something analogous for, say, `forall' and `exists'.)

It seems like an unnecessary constraint to me, but I don't care much one
way or the other.  If we do make this change, we can no longer claim
for-each returns an (the) unspecified value.

Kent