Re: tsearch is non-multibyte-aware in a few places

I wrote:
> This is safe if and only if t_isspace is never true for multibyte
> characters ... can anyone think of a counterexample?

Non-breaking space is a counterexample, so I pg_mblen-ified those
loops too.  Fortunately this code only executes during dictionary
cache load, so a few extra cycles aren't too critical.
        regards, tom lane