ring-bell-function doesn't seem to work on OS X

[Will Farrington]

I've tried (setq ring-bell-function nil) to no real avail.

(setq visible-bell t) *works*, but it's hardly a fix for the  
underlying issue of my not wanting to be annoyed by flashes and beeps.

This has been tested on both recently-compiled Emacs 23, and on the  
latest Carbon Emacs.