Installed automake 1.15, which gives aclocal-1.15, and now GCC 6.2.0 builds.
Had a long drawn out “ahhhhhhhhhhhhhhhh” moment earlier. I had downloaded the 20GB of source which is every released version of GCC – in the /tmp dir. I had to reboot, after accidentally removing my normal user from sudo group (and so loosing access to root).
The build script downloads the sources, of course. I’ll just need to run it again.
So it’s kinda looking like I can prolly build 4.2.0 up to 6.2.0, inclusive.
4.1.2 is probably going to be a headache, but we’ll see.
I expect to spend the weekend trying to build on the other platforms.