OK, great, I was able to successfully build pre120 on a gcc-4 system, Maxima build is in progress, and it has gotten past the point where pregexp.lisp is compiled, so I guess that's okay now.
The new executable identifies itself as "GCL (GNU Common Lisp) 2.6.12 ANSI Fri Apr 22 15:51:11 UTC 2016". I would like to recommend pretty strongly to equip GCL with a more precise version string. Wouldn't it be a lot better to say "2.6.13pre120" as the version identifier? If any date is given, it seems like it should be either the timestamp of the tagged commit, or the time at which the executable was built, dunno what makes more sense. I'll keep you posted about the Maxima build. best, Robert