There should be an automated way for re-generating code, i.e. running Kranc and autoconf.
Often, projects have a script "autogen.sh" that does so. This can't be a makefile, since this has to generate configure, which needs to run to generate the Makefile.
In our case, autogen.sh would (unconditionally) run autoconf to generate configure, and would check each thorn for certain scripts/makefiles that then have the opportunity to re-generate code (if needed). For example, we could check for files "autogen.sh" in each thorn's main directory. E.g. McLachlan would contain the command "cd m; make" there.