Running xgo on Mac M3 cross compiling to Linux x86_64 has a link error

[rcowham]

/usr/local/go/pkg/tool/linux_arm64/link: running x86_64-linux-gnu-gcc failed: exit status 1 /usr/lib/gcc-cross/x86_64-linux-gnu/9/../../../../x86_64-linux-gnu/bin/ld: cannot find /usr/lib/x86_64-linux-gnu/libm-2.31.a /usr/lib/gcc-cross/x86_64-linux-gnu/9/../../../../x86_64-linux-gnu/bin/ld: cannot find /usr/lib/x86_64-linux-gnu/libmvec.a

I discovered by looking inside the Docker container, that the relevant libraries were located in /usr/x86_64-linux-gnu/lib/

Tried a few things to fix, but ended up with modifying the Dockerfile and adding this near the end:

RUN ln -s /usr/x86_64-linux-gnu/lib/* /usr/lib/x86_64-linux-gnu/

Seems a bit clunky but works...