bug#12051: 24.1; rcirc-send-message doesn't take multibyte into account.

[Eli Zaretskii]

> From: Li Ian-Xue <b4283@bephor.org>
> Date: Wed, 15 Aug 2012 09:59:05 +0800
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > Isn't it better and simpler to split the string after it is encoded
> > inside rcirc-send-string?
> But by then one wouldn't know at which byte to cut. For example when
> it's a multibyte-ascii mixed string.

You can always stop at known characters, like whitespace.

Anyway, another way is simply to assume the worst possible expansion
ratio, and estimate the byte count before encoding.