bug#34907: Go compiler refers to multiple versions of GCC

[Royce Strange]

Hello.

It has been a while and I believe that the core-updates 
from that time got merged.
The go compiler no longer appears to refer to multiple versions of GCC.

------
$ guix --version
guix (GNU Guix) 2971ed57345ee4e00058efeaf27c6a0790fdc9dd

$ guix gc --references $(guix build --no-grafts go)
/gnu/store/57xj5gcy1jbl9ai2lnrqnpr0dald9i65-coreutils-8.32
/gnu/store/8mgy1zpcsg5hnkgdar0vrkqpssw87fay-tzdata-2019c
/gnu/store/8zvc5mvk0xm3ygrxsgpyy5ilxb5rzjry-perl-5.30.2
/gnu/store/fa6wj5bxkj5ll1d7292a70knmyl7a0cr-glibc-2.31
/gnu/store/mdxmdhrlkgdik6ay9pzmmy8mjcbibpwb-gcc-7.5.0-lib
/gnu/store/pwcp239kjf7lnj5i4lkdzcfcxwcfyk72-bash-minimal-5.0.16
/gnu/store/rn75fm7adgx3pw5j8pg3bczfqq1y17lk-gcc-7.5.0
/gnu/store/w8gjhcw6a16rk1dvxa97bz2znal5fihm-go-1.13.9
/gnu/store/zfbbn61ij7w0bl4wbrwi87x5ghqx968c-net-base-5.3
/gnu/store/pwcp239kjf7lnj5i4lkdzcfcxwcfyk72-bash-minimal-5.0.16
------

Going to go ahead and close.
(note: there is bug#39400 to look into why go retains a reference to GCC)