[bug#65317] [PATCH v2 1/1] gnu: Add go-1.21.

[Katherine Cox-Buday]

This version solves the problem by reversing the symlinking done during 
install as suggested in https://github.com/golang/go/issues/61921. 
Instead of:

- mv bin $out/bin
- ln -s ../../bin $out/lib/go/bin

we need to do:
- mv bin $out/lib/go/
- ln -s lib/go/bin $out/bin

This is because GOROOT_FINAL no longer has the intended effect and the 
binaries are expecting binaries to be run from GOROOT which is $out/lib/go.