main/gcc: add support for gcc-go

This adds support for gcc-go using libucontext-dev. Additionally, several patches are required to make this work with musl libc. These have been taken form Adélie Linux. However, Adélie Linux still uses gcc 8.X, I had to add two additional patches to make gcc-go 10.X compile. I would like to emphasize that I have no experience whatsoever with the gcc code base and the two patches added by myself are therefore shitty.

This builds fine locally on x86_64.