$ sudo apt-get update
$ sudo apt-get install gcc-5-plugin-dev-s390x-linux-g

gcc-5-plugin-dev-s390x-linux-g is installed in your system.

Make ensure the gcc-5-plugin-dev-s390x-linux-g package were installed using the commands given below,

$ sudo dpkg-query -l | grep gcc-5-plugin-dev-s390x-linux-g*

You will get with gcc-5-plugin-dev-s390x-linux-g package name, version, architecture and description in a table

gcc-5-plugin-dev-s390x-linux-g package basic information: