Install GLib cmake helper files

GLib is always/mostly required when building wireshark plugins. These cmake fiels help finding the install glib components

Change-Id: Ie59b50bf8c53c367d4bf89f53db5ae31e97e0575
Reviewed-on: https://code.wireshark.org/review/5252
Petri-Dish: Anders Broman <a.broman58@gmail.com>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Anders Broman <a.broman58@gmail.com>