[Bug: 21.5-b28] Could you please turn on `RE_CHAR_CLASSES' for XEmacs?

[Stephen J. Turnbull]

Steve Youngs writes:

 > It would be interesting to learn how GNU/Emacs copes with [Mule and
 > POSIX character classes].  Can somebody with a recent Emacs let me
 > know?

I'll bet it works correctly, they completely redid the regex engine
for 21 or 22.  It probably still uses the same API, though, so it
might be pretty port-able.