Lack of recognition of --enable-mule with configure.ac, autoconf 2.62

[Stephen J. Turnbull]

Aidan Kehoe writes:

 > Stephen, were you seeing messages like the following when you tested the
 > corresponding change? What version(s) of autoconf did you test it
 > with?

No, but autoconf shouldn't have anything to do with this.  This is a
shell syntax error, and autoconf will just pass it through.  I don't
understand why I don't see these because they're obviously syntax
errors, and my configure is dated newer than my configure.ac. ... I
don't know how it happened, but that is not a configure generated from
that configure.ac.  Sorry, my bad somehow.

The obvious patch is the correct one, just complete the syntax as you did.

I'll try to get to this later this evening.