Heh. It's pilot error all the way up at the beginning. GCC releases did ship these files, and they did it by using maintainer mode, which was generally a pain for those not maintainers. Which also explains why I was confused about the build. I definitely built it with the source on read-only file systems back in the day.

https://www.gnu-pascal.de/standards.html (from 2000.)

"Naturally, all the source files must be in the distribution. It is okay to include non-source files in the distribution, provided they are up-to-date and machine-independent, so that building the distribution normally will never modify them. We commonly include non-source files produced by Bison, lex, TeX, and makeinfo; this helps avoid unnecessary dependencies between our distributions, so that users can install whichever packages they want to install."