[gnome-builder/wip/gtk4-port] plugins/meson-templates: add missing license headers

[Christian Hergert <chergert src gnome org>]

commit e65a4f8919c407008062fad1d891e05a14aef2c7
Author: Christian Hergert <chergert redhat com>
Date:   Wed Jun 8 14:19:34 2022 -0700

    plugins/meson-templates: add missing license headers
    
    GPL is a file-based license, and our default, so these should be placed
    on the top of sources we create.

 src/plugins/meson-templates/resources/src/application-gtk4.rs | 2 ++
 src/plugins/meson-templates/resources/src/main-gtk4.rs        | 2 ++
 src/plugins/meson-templates/resources/src/window-gtk4.rs      | 2 ++
 3 files changed, 6 insertions(+)
---
diff --git a/src/plugins/meson-templates/resources/src/application-gtk4.rs 
b/src/plugins/meson-templates/resources/src/application-gtk4.rs
index 9d2b56cb3..0314259a8 100644
--- a/src/plugins/meson-templates/resources/src/application-gtk4.rs
+++ b/src/plugins/meson-templates/resources/src/application-gtk4.rs
@@ -1,3 +1,5 @@
+{{include "license.rs"}}
+
 use glib::clone;
 use gtk::prelude::*;
 use gtk::subclass::prelude::*;
diff --git a/src/plugins/meson-templates/resources/src/main-gtk4.rs 
b/src/plugins/meson-templates/resources/src/main-gtk4.rs
index abafbd171..25e5dab99 100644
--- a/src/plugins/meson-templates/resources/src/main-gtk4.rs
+++ b/src/plugins/meson-templates/resources/src/main-gtk4.rs
@@ -1,3 +1,5 @@
+{{include "license.rs"}}
+
 mod application;
 mod config;
 mod window;
diff --git a/src/plugins/meson-templates/resources/src/window-gtk4.rs 
b/src/plugins/meson-templates/resources/src/window-gtk4.rs
index 1237231d3..23732815a 100644
--- a/src/plugins/meson-templates/resources/src/window-gtk4.rs
+++ b/src/plugins/meson-templates/resources/src/window-gtk4.rs
@@ -1,3 +1,5 @@
+{{include "license.rs"}}
+
 {{if is_adwaita}}
 use adw::subclass::prelude::*;
 {{end}}