gnumach-dev software package provides GNU version of the Mach microkernel, 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 gnumach-dev
gnumach-dev is installed in your system.
Make ensure the gnumach-dev package were installed using the commands given below,
$ sudo dpkg-query -l | grep gnumach-dev *
You will get with gnumach-dev package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | Development |
| Package | gnumach-dev |
| Version | 2:1.7+git20160921-1 |
| Description | GNU version of the Mach microkernel |
| Sub Section | devel |