Checks that autotools generated files were re-generated correctly

[Martin Jambor]

Hello,

I have inherited Martin Liška's buildbot script that checks that all
sorts of autotools generated files, mainly configure scripts, were
re-generated correctly when appropriate.  While the checks are hopefully
useful, they report issues surprisingly often and reporting them feels
especially unproductive.

Could such checks be added to our server side push hooks so that commits
introducing these breakages would get refused automatically.  While the
check might be a bit expensive, it only needs to be run on files
touching the generated files and/or the files these are generated from.

Alternatively, Maxim, you seem to have an infrastructure that is capable
of sending email.  Would you consider adding the check to your buildbot
instance and report issues automatically?  The level of totally
false-positives should be low (I thought zero but see
https://gcc.gnu.org/pipermail/gcc-patches/2023-November/635358.html).

Thanks for any ideas which can lead to a mostly automated process.

Martin