build: Make network mandatory on every linux

In a recent commit[0], bluetooth, network and wacom panels were made
mandatory on every linux except on S390 systems. However, the
network panel should also be mandatory on S390 systems running
linux.

This changes the conditions to build bluetooh, network and wacom
panels.

https://bugzilla.gnome.org/show_bug.cgi?id=792641

[0] https://git.gnome.org/browse/gnome-control-center/commit/?id=a2b20a65c