when force software skinning is off, the actual playing FPS does not match the printed FPS

[snougo]

Godot version:

3.2.4 beta4

OS/device including version:

Issue description:

it seems that when force software skinning is off(it's off by default), Vsync doesn't work even Vsycn is on? and the actual playing FPS does not match the printed FPS, not sure is this is only appear on Mac or not, see the video
https://youtu.be/vn76LtOQcis
also you can download the video if you want
https://drive.google.com/file/d/1FqNY6b_0-5yLyd6l4HYjT_V0QuB7_Vg3/view?usp=sharing

Minimal reproduction project:

https://drive.google.com/file/d/1S8FRvCkftLBz26qBgIn1WUxtmwz_CsJZ/view?usp=sharing

[snougo]

I think this issue had be sloved by this PR #48555, again thanks and awesome work @lawnjelly