Consistent autoconf version

[Chris Hegarty]

Hi,

Sorry if this has come up before, but I cannot find anything in the 
archives.

Is it possible to agree an autoconf version to use to generate the 
checked in generated-configure.sh?

I recently had to merge, and regenerate this file, and found versions 
that were generated with 2.67, 2.68, and 2.69. Using such different 
versions makes it nearly impossible to see the relevant diffs in 
generated-configure.sh. While using the same version greatly, but not 
completely, simplifies the number of changes.

Is there any reason why not to agree a specific version?

-Chris.