As far as I can tell the developer is using Fibers on Windows and boost::context on all other operating systems. You can see that he has a forward declaration in "libgo/context/fcontext.h" and then links against the respective boost assembly files in the CMakeLists.txt.
Ah, correct. He's using asm files for fcontext from boost.context. Looks like those are copied into his tree from boost during build phase, and those files were the only I found. Thanks for pointing out. I maybe will need to test it on ARM one day, now I have peace of mind regarding ARM.