bug#17702: 24.3; insert-char no longer inserts "bell" control character

[Stefan Monnier]

> There's no need for Emacs to recognize yet another set of names, it
> already looks in the 'old-name' property of the characters, and
> considers them as completion candidates for "C-x 8 RET".
> This is not an issue with missing data; this is an issue with how we
> present that data to the user.

Upon further investigation, BELL seems to be the only char who doesn't
have a new-name and whose old-name is shadowed by some other char's
new-name.  So rather than change the code to handle such situations,
I special-cased BELL.


        Stefan