bug#5981: 24.0.50; Attempt to set a constant symbol: enable-multibyte-characters

[Stefan Monnier]

> With today's trunk, trying to display the HELLO file, like this:

>   emacs -Q
>   C-h H

> Causes Emacs to signal an error:

>    Attempt to set a constant symbol: enable-multibyte-characters

Fixed.
The problem was that view-hello-file did
(setq-default 'enable-multibyte-characters) so as to "DTRT" in
a unibyte session.  The previous code had a bug which made it allow this
even though enable-multibyte-characters is read-only.  I've fixed this
bug in the new variable code, which is why you now saw this error.

Since unibyte sessions are deprecated, I just removed the code (the
alternative would have been to revert to using
default-enable-multibyte-characters, since this variable has the curious
property of being real-only except when accessed via its
default-enable-multibyte-characters alias: another good reason to
dislike it).


        Stefan