Consistent autoconf version

[Chris Hegarty]

> ...
> I'm guilty of submitting with all three versions, depending on if I'm
> working on Ubuntu, Solaris, Windows or Mac. I too find it convenient
> when the versions match and if we decided on a specific version, I would
> just install that one from source on the machines I'm using. The build
> of autoconf takes a couple of seconds and has so far never failed for
> me, so it's not unreasonable or hard.

Right that is my understanding too. I have a single machine that I use 
for regenerating the generated-configure, and I will simply setup 
whatever version is required.

I don't think we need a hard mandate, just a softer agreement to use a 
specific version, to minimize noise. If someone cannot use that version, 
then so be it, but if possible then it should be encouraged.

-Chris.