
When specified, the project is installed to a separate destdir inside the container instead of the container's root filesystem. This can be used to install several projects into a common extension directory: ``` $ (cd mutter; meson-build.sh --sysext) && (cd gnome-shell; meson-build.sh --sysext) ``` We will later add a separate command to extract the directory from the container and turn it into a system extension suitable for use with systemd-sysext. Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/3498>