gccgo-5-s390x-linux-gnu software package provides GNU Go compiler, you can install in your Debian 9 (Stretch) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install gccgo-5-s390x-linux-gnu
gccgo-5-s390x-linux-gnu is installed in your system.
Make ensure the gccgo-5-s390x-linux-gnu package were installed using the commands given below,
$ sudo dpkg-query -l | grep gccgo-5-s390x-linux-gnu *
You will get with gccgo-5-s390x-linux-gnu package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | Development |
| Package | gccgo-5-s390x-linux-gnu |
| Version | 5.4.0-6cross1 |
| Description | GNU Go compiler |
| Sub Section | devel |