Should the make_xxx scripts be run at build time?

[Francois Gouget]

I'm excluding make_opengl from this discussion because it needs to 
download files so it's best to avoid having to run it.

But the various make_errors, make_vulkan and make_fir scripts could 
potentially generate the relevant files at build time.

The question comes up because either the TestBot needs to detect changes 
to their dependencies and rerun them when needed, or the Wine build 
system needs to do it.

The latter option has some caveats:
* These scripts depend on tools like awk, perl and Python 3. We may 
  not want Wine to depend on those for its build.
* Generating files like dxerr8/errors.h at build time breaks makedep 
  because it fails to find the header.

Any opinions on this?
Hints on how to deal with makedep?