Return exit code from `gio::Application::run()` from `main()`

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-rs/-/merge_requests/1065>

utils/fallbackswitch/examples/gtk_fallbackswitch.rs

@@ -196,7 +196,7 @@ fn create_ui(app: &gtk::Application) {
     });
 }
 
-fn main() {
+fn main() -> glib::ExitCode {
     gst::init().unwrap();
     gtk::init().unwrap();
 
@@ -206,5 +206,5 @@ fn main() {
     let app = gtk::Application::new(None::<&str>, gio::ApplicationFlags::FLAGS_NONE);
 
     app.connect_activate(create_ui);
-    app.run();
+    app.run()
 }

utils/livesync/examples/gtk_livesync.rs

@@ -158,7 +158,7 @@ fn create_window(app: &gtk::Application) {
     window.show();
 }
 
-fn main() {
+fn main() -> glib::ExitCode {
     let app = gtk::Application::new(
         Some("gtk-plugins-rs.gtk-livesync"),
         gio::ApplicationFlags::FLAGS_NONE,
@@ -171,5 +171,5 @@ fn main() {
     });
 
     app.connect_activate(create_window);
-    app.run();
+    app.run()
 }

utils/togglerecord/examples/gtk_recording.rs

@@ -326,7 +326,7 @@ fn create_ui(app: &gtk::Application) {
     });
 }
 
-fn main() {
+fn main() -> glib::ExitCode {
     gst::init().unwrap();
     gtk::init().unwrap();
 
@@ -336,5 +336,5 @@ fn main() {
     let app = gtk::Application::new(None::<&str>, gio::ApplicationFlags::FLAGS_NONE);
 
     app.connect_activate(create_ui);
-    app.run();
+    app.run()
 }

video/gtk4/examples/gtksink.rs

@@ -141,7 +141,7 @@ fn create_ui(app: &gtk::Application) {
     });
 }
 
-fn main() {
+fn main() -> glib::ExitCode {
     gst::init().unwrap();
     gtk::init().unwrap();
 
@@ -150,9 +150,11 @@ fn main() {
     let app = gtk::Application::new(None::<&str>, gio::ApplicationFlags::FLAGS_NONE);
 
     app.connect_activate(create_ui);
-    app.run();
+    let res = app.run();
 
     unsafe {
         gst::deinit();
     }
+
+    res
 }