The test-gmod project now builds without any hand-written Makefile, building it by using projgen to generate a makefile then make to build it now works!
I'm pretty happy with it, there's a couple things I might want to fix/add, but for now it's functionally ready.
Now I can probably focus on building a Containerfile for the build image.
This commit adds `projgen`, a very simplistic project generator.
Some knobs to the build system were added to ensure that only the
needed parts will build with each end (building the GMod module won't build projgen
since that isn't needed on the host)
The fun part will be figuring out how to jail things properly