bug#64391: buffer narrowing slowdown regression in emacs 29

[Stefan Monnier]

> Well, there's at least something that could be fixed in the manuals.
> I admit I had never read the "Special Forms" section, and if the manual had
> been consistent about the special form vs. macro distiction, perhaps
> I wouldn't have confused these two similar, but subtly different, notions.

At the same time, for the ELisp programmer, this distinction is just an
implementation detail (except for rare corner cases where the programmer
needs to look at the output of `macroexpand`).  What is a macro and what
is a special form has changed in the past and will likely change again
in the future (e.g. `defun`, `defmacro`, and `prog2` are now macros but
used to be special forms).


        Stefan