Run regen-configure script if available

[sethmlarson]

Closes #83 @Yhg1s was this the fix you were imagining?

[Yhg1s]

I guess this could work, but it's not what I had in mind, no. I had in mind just running the steps needed to regen configure:

     subprocess.check_call(
        [db["git_repo"] / "Tools/build/regen-configure.sh"],
     )

... but that will only work for 3.12 and later. 3.10 and 3.11 still require the use of podman/docker and Christian's images. We could backport the regen-configure script to those releases and make it then run docker the way the makefile currently does, I guess. (@pablogsal for that idea). I don't think we want to make 3.10/3.11 use autoconf 2.71 instead of the modified 2.69 from Christian's images at this point.

[sethmlarson]

@Yhg1s That makes sense, I'll move forward with backporting that script instead.

[sethmlarson]

@Yhg1s I've changed course on this since updating the builds of 3.11 and prior was closed, instead now we look for the regen-configure.sh script and fallback to the prior implementation using Docker. Let me know what you think.