ui/gtk: update monitor interval on egl displays

When running QEMU's GTK UI without EGL or OGL, the
gd_monitor_update_interval function gets executed and the display refresh
rate gets updated accordingly. However, when using EGL or just regular
OGL, the function never gets executed.

Which is why I decided that the function should be in gd_egl_refresh
where the display output gets updated, in the same vain as how it's done
for normal GTK UIs (aka. those without EGL) - in it's display refresh
function.

Since the gd_monitor_update_interval function now is exposed, we are
going to use it to update the refresh rate.

Signed-off-by: Nikola Pavlica <pavlica.nikola@gmail.com>
Message-Id: <20210114140153.301473-3-pavlica.nikola@gmail.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

ui/gtk-egl.c

@@ -113,6 +113,9 @@ void gd_egl_refresh(DisplayChangeListener *dcl)
 {
     VirtualConsole *vc = container_of(dcl, VirtualConsole, gfx.dcl);
 
+    vc->gfx.dcl.update_interval = gd_monitor_update_interval(
+            vc->window ? vc->window : vc->gfx.drawing_area);
+
     if (!vc->gfx.esurface) {
         gd_egl_init(vc);
         if (!vc->gfx.esurface) {