ui/gtk: Update the refresh rate for gl-area too

ui/gtk: Update the refresh rate for gl-area too

This is a bugfix that stretches all the way back to January 2020,
where I initially introduced this problem and potential solutions.

A quick recap of the issue: QEMU did not sync up with the monitors
refresh rate causing the VM to render frames that were NOT displayed
to the user. That "fix" allowed QEMU to obtain the screen refreshrate
information from the system using GDK API's and was for GTK only.

Well, I'm back with the same issue again. But this time on Wayland.

And I did NOT realize there was YET another screen refresh rate
function, this time for Wayland specifically. Thankfully the fix was
simple and without much hassle.

Thanks,
Nikola

PS: It seems that my patch has gone missing from the mailing list,
hence I'm sending it again. Sorry for any inconveniences.

Signed-off-by: Nikola Pavlica <pavlica.nikola@gmail.com>
Message-Id: <20211024143110.704296-1-pavlica.nikola@gmail.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>