[autoconf-conversion] Something to start with

[DJ Delorie]

> [I am a little worried.  I ran into what looks like a cache
> incompatibility; I configured libiberty using 2.50, backed down to the
> 2.13 configure script, did it again, and got quoting errors in
> config.cache.  But I can't reproduce it now, so I'm only a little
> worried.]

Yup, we know about that.  2.50 might not be usable; we might need some
other 2.5x that's fixed the cache bug.  Or we might need to disable
the cache for the interim.