solution for contemporary gcc version incompatibility

[gregm123456]

This doesn't seem to build with me for contemporary (2023) versions of gcc on ubuntu.

However, this little shell script uses docker to build a container with gcc 4.8, build poly3d, and write the compiled binary back to the local file system:

#!/bin/bash
git clone https://github.com/stgl/poly3d.git
cd poly3d
docker run --rm -v "$PWD":/usr/src/myapp -w /usr/src/myapp gcc:4.8 make

The created poly3d runs fine (ubuntu 22).