Re: new cleanups

[masinter.pa@Xerox.COM]

Users can rely on EVALHOOK more than they can rely on BREAK. EVALHOOK is
defined as 'a facility that is useful when it makes sense'. Conformal
implementations should be constrained to clearly document whether their
implementation is 'interpreted' or 'compiled', and EVALHOOK's behavior is
well specified: it affects evaluation of 'interpreted' forms and does not
affect the evaluation of 'compiled' forms. It is not true that "... users
can't rely on EVALHOOK doing anything meaningful." It is true that the
behavior of EVALHOOK can vary, in certain well constrained ways, from one
implementation to the next.